Furthermore, they improve the mechanical and thermal properties of the polymer and ceramic solid-state electrolytes (SSEs). Overall, the enhancements endowed by GBMs will address the challenges that are stunting the proliferation of SSBs. Solid-state batteries (SSBs) have emerged as a potential alternative to conventional Li-ion batteries (LIBs) since they are safer and offer higher energy density. Despite the hype, SSBs are yet to surpass their liquid counterparts in terms of electrochemical performance. This is mainly due to challenges at both the materials and cell integration levels. Various strategies have been devised to address the issue of SSBs. In this review, we have explored the role of graphene-based materials (GBM) in enhancing the electrochemical performance of SSBs. We have covered each individual component of an SSB  and highlighted the approaches using GBMs to achieve stable and better performance. The recent literature shows that GBMs impart stability to SSBs by improving Li SHE)  polymer was demonstrated . The ele0 cycles d. The ca0.5 for 1 vol% to 2.4 MPa.m0.5 for 5 vol% , ceramic SSEs do face problems such as low fracture toughness, especially when operated under stack pressures. Any tiny microscale fracture in the bulk of electrolyte provides paths for Li dendrites to sneak through that poses a risk of cell short circuit ,90. It ir 5 vol% a. It wasr 5 vol% c,d, wherr 5 vol% e that th7P3S11 SSE particles results in a stable and efficient all-solid-state battery performance. The synthesis of GO@LPS materials was performed using a simple facial technique where GO and LPS were mixed in acetonitrile followed by an annealing step as shown in + ions, GO is reduced to rGO; however, since a very small amount is added (~1 wt%), no percolation network is established. This was confirmed when the electronic conductivity of the electrolyte was 5 orders of magnitude lower than the ionic conductivity. Stable Li stripping/platting voltage profiles were observed for more than 600 h, unlike the uncoated LPS that short-circuited even before reaching 50 h of cycling. The Li|GO@LPS|LCO cells performed much better than cells based on only LPS electrolyte as shown in + ion flux at the interface.Another work explored a different role of GO in a sulfide LPS SSE . Due to −1. It is well known that sulfur as an electrode in liquid electrolytes is problematic due to the dissolution and “shuttle effect” of polysulfides, which greatly decrease cycle life and specific capacity. Replacing the liquid electrolyte with the SSEs can somehow address the polysulfide dissolution, and improve the safety and cycle stability. However, integrating sulfur cathodes with SSEs can increase the cell resistance due to poor electrode|electrolyte contact, although, some solutions have been found for this problem [GBM-enhanced cathode materials have performed well when integrated with different SSEs. Among various cathodes, sulfur is a popular choice due to its high theoretical capacity of 1672 mAh g problem . In addi problem . The ion problem ,99. Gene2S-24%P2S5-1%P2O5 electrolyte layer was inserted between the LGPS electrolyte layer and the lithium anode to avoid any undesired reactions between lithium metal and LGPS (−1 at 1.0 C)  b and lon2 gel polymer electrolyte (GPE) film. The cell exhibited a high initial specific discharge capacity (809 mAh g−1) and maintained a reversible discharge capacity of 413 mAh g−1 after 50 cycles under a 0.2 C rate. The cycling performance of the cell indicates that the combination of the S/GNS composite cathode and GPE plays a significant role of retarding diffusion of the polysulfides out of the cathode and suppressing their transport towards the anode side. The rate capability performance was also investigated, and the results indicated that the cell delivers a reversible discharge capacity of 638 mAh g−1 at 0.1 C. The high-rate operation was ascribed to the enhanced conductivity of the GNSs, which act as nano-current collectors, and the good ionic conductivity of the GPE.In another work , a sulfu−1 and favorable cycling performance of 740 mAh g−1 after 200 cycles. The interaction between the rGO and sulfur not only enhanced electronic conduction in the cathode but also suppressed the volume change during the conversion reaction.Kızılaslan et al. investigated the effects of two different synthesis methods of rGO-S composites cathodes, including the melt-diffusion method and solution-based techniques . They ar2ZnSnS4/GO) via a hydrothermal approach. GO could deposit and adhere to the surface of the materials due to its hydrophilic nature as it contains more oxygen contents as compared to other forms of graphene. The results revealed a discharge capacity of 645 mAh g−1 after 50 cycles (2ZnSnS4/graphene (CZTS/graphene) with a weight ratio of 2:1 using a bilayer solid electrolyte (LGPS and 70%Li2S-29%P2S5-1%P2O5). Furthermore, a good rate of performance was observed where discharge capacities ~527, ~439, and ~278 mAh g−1 were delivered at 100, 250, and 1000 mA g−1, respectively. TEM and HRTEM images, as shown in Wan et al.  designed0 cycles c for Cu22S4, CuCo2S4/graphene, and CuCo2S4/graphene@Li7P3S11 nanocomposites were studied [2S4 aqueous solutions were mixed and dried via hydrothermal processes, resulting in composites as shown in 7P3S11 was coated on the surface of CuCo2S4/graphene nanosheets . To improve Li anode performance, the incorporation of novel nanostructured materials such as graphene with Cu is being actively considered [−2  is a preferred current collector for Li anode due to its electrochemical stability at low potentials  and natural graphite (NG) demonstrated better rate capability and capacity retention than electrodes without rGO  was created by using monolayer graphene grown on a Cu foil as the electrode (∼25 µm thick) and integrated with poly-(ethylene glycol) borate ester thin SPE [Flexible SSBs will require the development of not only flexible SSEs but also thin and flexible electrodes ,114,115.thin SPE . The pra−2 S cm−1 have been reported [+ ions in a solid-state system depends on the following two important factors: firstly, the (electro-)chemical stability at the interface; and secondly, the contact intimacy and mechanical robustness. Once Li contacts the SSE, interphase layers start to form due to Li reaction and electrolyte decomposition [+ ion transport [+ ions to form alloys that would ensure stable interfacial contact.With SSEs, the focus has been on enhancing the room temperature ionic conductivities of the electrolyte to reach or even surpass those achieved for conventional organic liquid electrolytes. There has been success on this front, especially with ceramic electrolytes where room temperature ionic conductivities >10reported ,118,119.reported . The eleposition ,120. Intransport ,122. Furransport ,125,126.+ → LiF + Gr), GF was converted to graphene and LiF that acted as an interlayer between LFP and LLZO, as shown in +. Since LLZO is very brittle in nature, achieving an intimate electrode|SSE contact is always an issue. The authors claim that a flexible graphene/LiF interlayer ensures an intimate contact that imparts stability to the Li+ ion transport; consequently, an improved battery performance (140 mAh/g after 60 cycles) is achieved than cells without interlayers (+ → 2Li+ + rGO + H2O) and subsequent coating of poly(propylene carbonate) results in the formation of an in situ rGO that acts as an interlayer. The GO-modified electrolyte showed good properties such as a wide electrochemical window (up to 4.8 V), ionic conductivity (~2 × 10–4 S cm–1), and a high ionic transference (0.9). When the interface-modified SPE was paired with Li metal and NCM622 electrodes, an initial specific capacity of about 160 mAh g−1 at 0.5 C was achieved. While there was some capacity decay, nevertheless, ~100 mAh g−1 was still maintained after 200 cycles. GO has also been used as a thin interlayer between Li and sulfide SSEs [7P3S11 (LPS) SSE from directly contacting Li metal, which otherwise would cause undesired reactions. In another work, coating GO thin layers on LiNi0.5Mn0.3Co0.2O2 (NMC532) and then integrating with a poly(propylene carbonate) based SPE helped retard the decomposition of PPC electrolyte that may be induced by the oxidized species (Ni3+ and Co4+) during the charging cycle of the cathode [Several reports demonstrate the use of graphene or GBMs at the electrode|SSE interfaces via simple facial approaches ,129,130.erlayers c. The foide SSEs . Here, t cathode . The imp+ conductive layers of LiC6, thus facilitating the uniform deposition of Li and inhibiting Li dendrite formation during long-term cycling.Graphene has also been demonstrated to help achieve better contact in a 3D architectural Li metal anode . ExistinIn this review, we have presented a summary of the recent progress in SSBs, with a focus on the role of GBMs in enhancing their electrochemical performance.Graphene exhibits novel electrochemical properties such as low charge transfer, wide potential window, excellent electrochemical activity, and fast electron transfer rate that could be useful for many applications, including LIBs. The synthesis involves chemical and/or electrochemical exfoliations of graphite to form a monolayer, FLG, or GNP graphene platelets optionally containing various functional groups. GBMs are particularly suitable since they are beneficial for each component  of an SSB as summarized in + ion transport via ordered channels provided by the 3D GO. The high mechanical strength imparted by GO has also encouraged the application of CPEs for flexible batteries. Furthermore, rGO has benefited ceramic SSEs by enhancing their fracture toughness, which could potentially be useful for inhibiting penetration of Li dendrites. It is worth mentioning that compared to less oxidized forms of GBMs, GO has various safety and regulatory hurdles that limit large-scale production. Therefore, the main applications for SSBs are mostly demonstrated at a lab-scale level.For SSEs, GO has been the most studied type so far due to its electronically insulating nature, hence excluding any possibility of electronic leakage or short-circuits, at the same time enhancing conductivities and improving mechanical and thermal properties. Ionic conductivity is improved by facilitating Li salt dissociation. Further, GOs can mechanically interlock with polymeric chains thanks to their 2D geometry, which reinforces the SPEs to achieve better mechanical properties. Lastly, SPEs based on GO can withstand higher temperatures thanks to their high thermal stability. In most of the works, the SSEs are composites of randomly oriented GOs and polymers. However, a few works have also explored the potential of using 3D GO as filler. In such structures, improved performances are observed due to enhanced LiThe role of GBMs in both cathodes and anodes is also of significant importance. Here, some of the advantages of rGO are to provide a large surface area for Li intercalation, offer high electronic conductivity to lower the electrode resistance, and suppress the agglomeration and deformation of the electrode nanostructures during cycling. In the case of the sulfur cathode, graphene can help to retard the diffusion of the polysulfides out of the cathode and suppress their shuttle towards the electrolyte and the counter electrode. Hence, not only inhibiting active material loss but also minimizing anode corrosion. They can also enhance particle-to-particle contact in transition metal oxide cathodes. On the other hand, graphene’s benefits for the anode are also substantial, such as its use as thin-film electrodes to store charge for miniature flexible thin-film batteries, with a Cu current collector to ensure less resistive Li|Cu contact, and as a template to achieve 2D morphologies for ceramic SSEs in a composite.+ ions to form alloys that would ensure an electrochemically stable and mechanically intimate electrode|SSE contact.Alongside their role in SSEs and electrodes, graphene has also the potential to be used as an interlayer at the solid–solid interface at the electrode|SSE junctions. This is mainly possible because of favorable traits of graphene such as mechanical robustness, structural flexibility, and reactivity with Li+ ion flow and minimize the risk of Li dendrites.The future is going to see an enormous demand for batteries with high storage capacity and faster charge rates. FLG and GNP with low oxygen content are becoming more commercially available and affordable and might offer a viable path once the development of graphene-enhanced SSBs gains momentum. To start with, stable SSBs should be designed that could challenge conventional LIBs in terms of performance metrics. Graphene’s role should be further explored in enhancing the electrochemical and mechanical properties of the SSEs, electrodes, and interfaces. Since GBMs have different roles for each component of an SSB, careful consideration should be given to tailoring their properties that can benefit the relevant material’s performance. GO, so far, has been the preferred material in academic research for enhancing SPEs properties. Oxidizing or altering GO’s surface chemistry by introducing new functionalized groups might improve its interaction with polymer molecules but also create more mass-production regulatory uncertainties from the health and safety standpoint. For electrodes, controlling the size and chemistry of the graphene’s micro and nanostructures will be very important. The roles of rGOs and FLG will be significant, especially in the design of electrodes. Here rGO and FLG should offer high surface area providing greater cites for Li to intercalate. They should have high electronic conductivity to help reduce cell polarisation and facilitate redox activity. Lastly, graphene, as an interface mediator, should have the mechanical flexibility to buffer the Li anode expansion and ensure a robust interfacial contact with the SSE. They should also adhere to the uneven surfaces at the electrode|electrolyte solid-solid junctions to fill up micropores that will regulate LiCurrently, the use of graphene in SSBs is still in an early stage. However, the near future is going to see an enormous demand for GBM-enhanced SSBs. To achieve the target performance, systematic research strategies should be developed, considering both performance and mass-production limitations. We believe that the pristine form of graphene is much more regulated, inexpensive, and commercially available, and therefore it is likely that more research will be performed on FLG and GNP in the near future, even though the properties of GO could be more suitable in certain cases. There will be a need for the development of more powerful in situ and operando characterization tools, which could provide insights into the interactions of GBMs with various components of an SSB. Further, computational studies as a supplement to experimental efforts may allow researchers to devise better strategies and design advanced solid-state energy storage systems.


TDP-43 proteinopathies is a disease hallmark that characterizes amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). The N-terminal domain of TDP-43 (NTD) is important to both TDP-43 physiology and TDP-43 proteinopathy. However, its folding and dimerization process is still poorly characterized. In the present study, we have investigated the folding/unfolding of NTD employing all-atom molecular dynamics (MD) simulations in 8 M dimethylsulfoxide (DMSO) at high temperatures. The MD results showed that the unfolding of the NTD at high temperature evolves through the formation of a number of conformational states differing in their stability and free energy. The presence of structurally heterogeneous population of intermediate ensembles was further characterized by the different extents of solvent exposure of Trp80 during unfolding. We suggest that these non-natives unfolded intermediate ensembles may facilitate NTD oligomerization and subsequently TDP-43 oligomerization, which might lead to the formation of irreversible pathological aggregates, characteristics of disease pathogenesis. The mislocalization and cytoplasmic ubiquitinated inclusions of transactivation response DNA-binding protein 43 kDa (TDP-43) are the major neuropathological hallmark in Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia  were added to each simulation box , having DMSO molecules 1,040 were allowed for energy minimized up to 50,000 steps applying steepest descent and conjugant gradients, respectively. Two steps ensemble process, NVT, and NPT were performed up to 1 nm to equilibrate the prepared systems. Berendsen thermostat , solvent accessible surface area (SASA), and root mean square fluctuation (RMSF) were evaluated by Gromacs utilities with MDTraj , radius of gyration . FEL was studied by applying the equation for Boltzmann inversion, Rg, RMSF, and SASA did not show significant changes and remained stable also. However, a slight decrease in Nc of NTD was observed during the simulation. Thus, to accelerate the unfolding process of NTD, the all-atom MD simulations in the presence of 8 M DMSO for 500 ns were carried out with higher temperatures, very similar to our previous studies  for 500 ns each were performed. The different structural order parameters were then analyzed to allow a detailed description of the NTD unfolding. We have previously reported the structural stability of NTD in water and in 8 M urea at 300 K  has been used for describing conformational changes associated with protein unfolding/folding pathways. Even though the protein’s free energy landscape can be rugged and high dimensional  of Nc with RMSD and mediates . The FELmediates . At 400 mediates . One of mediates . The FELRg. Interestingly, the significant overlap between these two FELs reveals excellent agreement for the reported configurations.Moreover, we have examined two FEL contour maps where the first FEL was calculated as a function of the Nc and RMSD pair and the second FEL was calculated as a function of Nc and Next, the FEL involving the number of intraprotein hydrogen (H)-bonds and Nc at 400 K and 450 K was constructed as shown in 2. At 400 K, W80 undergoes different extents of solvent exposure during unfolding, similar to the experimentally observed decrease in fluorescence  along with the increase in RMSD (~0.2 nm) during the simulation, suggesting the complete unfolding of the protein. These results, therefore, show that solvent exposure of W80 can occur on different time scales and is also depends on the temperature, indicating that the unfolding reaction is non-cooperative and is not all-or-none. However, it is not yet clear that the observed non-cooperativity is either due to the presence of a high concentration of DMSO or increased temperature.Next, we monitor the unfolding pathway of NTD at 400 K through the analysis of the evolution of the side chain SASA of W80 along with the Ca RMSD during 500 ns simulation . In the mulation . During The dynamic cross-correlation matrices (DCCM) analysis was further studied to illustrate dynamical information of proteins in two dimensions (Pandey et al., The prion-like CTD is largely involved in the aggregation of TDP-43 and most of the fALS mutations are located within this domain (Li et al., We have previously investigated the thermal unfolding of NTD in the presence of 8 M urea using all-atom MD simulations and showed that unfolding of NTD at 350 K occurs through the presence of different stable and meta-stable intermediate states. These unfolded intermediates share the properties of molten globule states stabilized largely by non-native hydrophilic interactions and are highly energetically frustrated. The non-native unfolded intermediate states might facilitate protein oligomerization and aggregation. Very recently, Vivoli-Vega et al.  biophysiDifferent chemical denaturing agents act differently on the protein unfolding process (Mukherjee et al., With this view, we here studied the unfolding of NTD as the structural and conformational integrity of the NTD is essential for the proper function of TDP-43. A detailed account of the unfolding and thermodynamics of the NTD has been delineated in 8 M DMSO at high temperatures using all-atom MD simulations. The unfolding process of NTD is characterized by the presence of different meta-stable intermediates at 400 K and 450 K along with the population of completely unfolded species at 450 K. The structural transitions during the unfolding indicated the appearance of helices along with increase in minor secondary structures like bend or turn. Thus, the computational insights of the unfolding pathway of NTD will help in understanding the full description of the TDP-43 folding/unfolding landscape.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.VK and AP designed the study. RL RS, and AP performed the experiments and calculations. RL, TK, AP, and VK analyzed the data. CY, RDS, AP, and VK wrote the main text with the contributions of AL and RP. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


In this article, polyurethane (PU)/epoxy (EP) interpenetrating polymer networks (IPNs) filled graphene aerogel (PEGA) was facilely fabricated by a one-step vacuum-assisted filling process. Effects of PU content on damping performance, thermal stability and mechanical properties of the PEGA composites were studied systematically. Results reveal that addition of graphene aerogel improves damping properties of PU/EP IPNs and increases the thermal decomposition temperature. Mechanical tests show that flexural strength, flexural modulus and Shore D hardness of the PEGA composites also improved by incorporation of graphene aerogel. The enhanced damping, thermal and mechanical properties of PEGA composites can be attributed to the uniform distribution of graphene sheets in the IPN matrix, which benefits from the three-dimensional interconnected porous network structure of the graphene aerogel used and good interfacial adhesion at the nanofiller-matrix interface. It is expected that the PEGA composites can be used as good structural damping materials in future. PEGA composites were facilely fabricated by a one-step vacuum-assisted filling method, and exhibited improved damping, thermal and mechanical properties. The requirement for practical engineering materials is that the tan δ value should be above 0.3 and temperature range of tan δ > 0.3 should be as wide as possible.8–10 However, good damping performance of polymers is usually limited to a narrow temperature range of Tg ± 10 °C, which limits their practical use.11 Many techniques have been used to enhance damping properties of polymers, such as creation of polymer blends,12,13 copolymers,14,15 and interpenetrating polymer networks (IPNs).8,16 IPN is a novel type of polymer alloy comprising two or more crosslinked polymers held together by physical entanglement, and it is promising material with broad Tg ranges and excellent damping performance.11 Polyurethane (PU)/epoxy resin (EP) IPNs, which integrate the advantages of polyurethane's high damping performance and epoxy resin's high mechanical behavior, have been widely studied in previous reports,9–11 with expectations of obtaining good structural damping materials. However, the addition of PU into EP matrix can lead to reduction of mechanical and thermal properties due to the low modulus and thermal stability of PU polymer.Loss factor , sodium nitrate , potassium permanganate , concentrated sulfuric acid , hydrochloric acid , and hydrogen peroxide  were purchased from Sinopharm Chemical Reagent Co., Ltd., China. All chemicals were used as received.Graphene oxide (GO) was prepared by a modified Hummers' method.3COCH3, AR) were supplied by Shanghai Macklin Biochemical Co., Ltd.Double-pack polyurethane (PU) 130T-A  was purchased from Ausbond. E51, which was used as the epoxy monomer, and poly(ethylene glycol) diglycidyl ether (PEGGE), another epoxide acting as flexibilizer, were bought from Shanghai Resin Factory Co., Ltd., China. 4,4′-Diaminodiphenylmethane (DDM), a high temperature curing agent, Jeffamine D-400, a soft curing agent utilized to increase ductility, and the solvent acetone  was added to 20 mL deionized water and stirred for 2 h to achieve a clear solution. Then, hydrazine hydrate (300 μL) was added dropwise into the above solution and stirred for several minutes. Following this, the mixture was sealed into a glass vial and placed in an oven at 95 °C for 12 h. Finally, the resulting hydrogel was washed with ethanol and deionized water several times to remove impurities and freeze-dried for 48 h to obtain graphene aerogel.2.3Epoxy E51 and polyalcohol were dried at 80 °C under vacuum for more than 6 h before use. A certain amount of curing agent DDM was dissolved in acetone and heated at 70 °C to obtain a clear solution. The schematic fabrication process of PEGA composite is shown in 2.4−1 under 35 kV and 200 mA. X-ray photoelectron spectra (XPS) were recorded using a Kratos Axis Ultra DLD spectrometer. Raman spectra were taken on a SENTERRA R200 Raman spectrometer with 532 nm laser excitation. Nitrogen absorption and desorption measurements were performed with an Autosorb IQ instrument. Surface area was calculated by the Brunauer–Emmett–Teller (BET) method. Scanning electron microscopy (SEM) images were obtained on a Hitachi S-4800 field-emission SEM operated at 10 kV. Pyrolysis processes of the samples were studied using thermogravimetric analysis  with a heating rate of 10 °C min−1 from room temperature to 800 °C under nitrogen atmosphere.X-ray diffraction (XRD) spectra were acquired by D/MAX2550/PC using Cu Kα radiation from 8° to 80° at a scan rate of 5°min3 were used. Material property tests were conducted in tension mode at the frequency of 1 Hz. Temperature range was from −15 to 100 °C at a heating rate of 5 °C min−1, and storage modulus (E′), loss modulus (E′′), and loss factor (tan δ) values were obtained simultaneously. Flexural tests were performed with a three-point bending fixture according to ASTM D-790. Specimens of dimensions 50.8 × 12.7 × 3 mm3 were subjected to bending with a support span of 25.4 mm at a constant cross-head speed of 2 mm min−1 on a universal testing machine . Values were taken from an average of at least five specimens. Shore D hardness was measured according to DIN EN ISO 868 with a portable Shore D measuring instrument with specimens of 50 × 10 × 3 mm3 and reported results were an average of at least five measurements.Dynamic mechanical measurements were performed on a DMA Q800 and rectangular specimens of 20 × 8 × 2 mm3.32,33 The C1s XPS spectrum of GO is shown in  PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>C/C–C, C–O, CO and O–CO, respectively. After reduction, as shown in 34−1 and is associated with structural defects caused by the functional groups. The G band can be found at 1576 cm−1 and is the characteristic of sp2-hybridized carbon–carbon bonds.35 For GO, peak area ratio of the D band to the G band is 1.58, while the ratio is 2.10 for graphene sheets. According to previous reports, increase in the ratio of A(D)/A(G) indicates that numerous but smaller sp2 carbon domains were formed.36 The results of XRD, XPS and Raman spectra indicate that GO was effectively reduced to graphene sheets by hydrazine hydrate.As shown in 2 adsorption–desorption isotherms of graphene aerogel exhibit the Type II hysteresis loop, which is characteristic of pores of different sizes.39,40 BET surface area of the graphene aerogel was determined to be 122.6 m2 g−1. Moreover, pore size distribution of graphene aerogel calculated by DFT method indicates a large proportion of mesopores with size distribution from 2.5 to 20 nm with peak pore diameter of approximately 2.8 nm , loss modulus (E′′) and loss factor (tan δ) of materials were recorded simultaneously. E′ values as a function of temperature. Storage modulus is an important property to assess load bearing capacity of a material and hence, high E′ value indicates high stiffness of material.4,5 It was found that E′ values of PU/EP IPNs are all lower than those of the epoxy resin and gradually decreased with increasing PU amount. As shown in E′ values of epoxy resin, PU/EP-20, PU/EP-40 and PU/EP-50 are 2074.9, 1862.9, 1292.0 and 225.9 MPa, respectively. After addition of graphene aerogel, storage modulus values of composites PEGA-20 and PEGA-40 were improved compared with those of the corresponding PU/EP IPNs and their E′ values were higher than that of epoxy resin near room temperature. This significant enhancement in mechanical performance of PEGAs can be attributed to the good dispersion of graphene sheets in the composites, which benefits from the three-dimensional network structure of graphene aerogel and the good interaction between graphene sheets and polymer matrix, which could be caused by the reaction between residual oxygen-containing functional groups of graphene sheets and the PU/EP mixture during the curing process.18,19 As shown in PEGAs were fabricated by filling the graphene aerogel with PU/EP mixture. The damping properties of the epoxy resin, PU/EP IPNs and PEGA composites were investigated by dynamic mechanical analyzer (DMA) and the parameters of storage modulus (E′′) is a measure of energy dissipated as heat per unit cycle under mechanical deformation and it is used to characterize viscosity of a material.1,8 It is evident that all the as-fabricated PEGAs show higher E′′ values than corresponding PU/EP IPNs, which indicates that PEGA composites could dissipate more mechanical vibration and noise into heat energy. The composite PEGA-40 displays the best loss modulus behavior at room temperature and its E′′ value represents an increase of about 977.9% compared to that of PU/EP-40 at the same temperature, which may be due to the graphene aerogel generating a high filler boundary sliding (filler–filler) and interfacial sliding (filler-matrix) under external dynamic loading, which dissipates more mechanical energy into heat.2,16δ) is defined as the ratio of storage modulus and loss modulus. Higher tan δ values indicate better energy dissipation capabilities of materials.39 Normally, service environment for most engineering damping materials is near room temperature; hence, the value of tan δ should be high and the temperature range of tan δ > 0.3 should be as wide as possible near room temperature.37 Loss factor values of epoxy matrix, PU/EP IPNs and PEGA composites as a function of temperature at 1 Hz are shown in δ) was 0.213 at room temperature and the temperature range of tan δ > 0.3 was from 43.3 to 85.7 °C. For PEGA-40, the tan δ value is 0.281 at room temperature and the temperature range of tan δ > 0.3 was from 25.5 to 81.2 °C, which covers the usual applied temperature range. Composite PEGA-50 exhibits the best tan δ value of 0.56 and the widest temperature range of tan δ > 0.3 of 81.7 °C from −1.3 to 80.4 °C. These results indicate that damping performance of PEGA composites are gradually improved with the increase in PU content.Loss factor , as reported in other studies.18,19,40 It can be observed that all the glass transition temperatures of PU/EP IPNs shift to lower temperatures and decrease with the increase in PU weight ratio due to addition of low Tg PU polymer. Furthermore, glass transition temperatures of composites PEGA-20 and PEGA-40 improved compared with those of corresponding PU/EP IPNs, while Tg of composite PEGA-50 is lower than that of PU/EP-50. In the PEGA composites, two possible factors influence their glass transition temperatures. On one hand, the added graphene aerogel can absorb the nitrogen-containing curing agent or isocyanate chains of PU, which can disturb the stoichiometric reaction of the polymers and thus lead to reduction of Tg by decreasing the crossing-linking density of the system. On the other hand, the wrinkled structure and higher stiffness of graphene sheets can constrain molecular mobility of the polymer chains in the substantial interphase zone around the nanosheets. Moreover, 3D graphene aerogel can provide higher surface area with more interphase zone in contact with the polymer matrix and thus shift Tg to higher temperature. The final effect on Tg will depend on the balance of these two effects, namely, influence on reaction conversion and molecular confinement, as reported by other studies.40,46,49,50 For composite PEGA-50, Tg decrease may be attributed to reduction of cross-linking density of the polymers functioning more during the complicated reaction system. As a result, reduced cross-linking density of the polymers leads to lower storage modulus of composite PEGA-50 when compared with that of PU/EP-50.16 In addition, it can be seen that the thermal stability of PU/EP IPNs is much lower than that of neat epoxy resin, which is due to the lower thermal stability of polyurethane.10,16 After the addition of graphene aerogel, the thermal stability of all the PEGA composites improved significantly compared with those of corresponding PU/EP IPNs. As shown in T5 (5% weight loss) of PEGA-20, PEGA-40 and PEGA-50 increased by 15.9, 6.3, and 6 °C, respectively, compared to corresponding IPN polymers. In addition, T10 of PEGA-20, PEGA-40 and PEGA-50 increased by 18.1, 13.7, and 6.7 °C, respectively. Moreover, residual weights at 700 °C of PEGA composites also increased compared to those of corresponding PU/EP IPNs. These results clearly indicate that introduction of graphene aerogel into PU/EP IPNs greatly enhanced thermal stability of the composites. The increase in thermal stability with addition of graphene sheets may be attributed to the higher heat capacity of graphene sheets compared to polymer matrix and a better barrier effect of graphene sheets, which retards the volatilization of polymer decomposition products due to the good dispersion and interface in PU/EP IPNs.41 In addition, the increased char residue can form a char barrier to protect the nanocomposite surface from oxygen and a mass and heat barrier to enhance the thermal stability.42 Similar phenomena have been reported in earlier studies, showing that addition of graphene sheets can improve thermal stability of the resulting composites.41,42TGA was used to assess thermal stability of the epoxy resin, PU/EP IPNs and PEGA composites; their thermograms are presented in 24 we examined the effect of graphene sheets on the mechanical properties of PU/EP IPNs. Flexural strength and flexural modulus of the as-fabricated materials are shown in 51–53 After addition of graphene aerogel, flexural strength and flexural modulus of all PEGAs improved compared with those of corresponding PU/EP IPNs. For PEGA-20, flexural strength and flexural modulus significantly improved, with values of 175.8 MPa and 2.83 GPa, exhibiting an increase of about 45.1 and 9.27%, respectively, compared with PU/EP-20, and the values are higher than those for epoxy resin. For composite PEGA-40, flexural strength significantly improved from 75.9 to 97.1 MPa and flexural modulus greatly enhanced from 0.28 to 0.53 GPa compared with PU/EP-40 IPN, showing an increase of about 27.9 and 89.3%, respectively. There are several possible reasons for the enhancement of mechanical performance of PEGAs. The three-dimensional porous network structure of graphene aerogel guarantees uniform distribution of graphene sheets in the matrix and also easily forms mechanical percolated networks in the composites, which is beneficial for stress transfer from the polymer matrix to the graphene sheets, thus leading to the improvement in the mechanical behavior of the PEGA composites compared to that of the PU/EP IPNs.21–23 In addition, graphene sheets have numerous residual oxygen-containing surface groups which can form hydrogen bonds or react with PU/EP mixture during the curing process, resulting in good interfacial adhesion at the nanofiller-matrix interface.19,26 Moreover, the two-dimensional geometry and large aspect ratio of graphene platelets may benefit the enhancement of composites' mechanical behavior.24Given the excellent elastic modulus (∼1100 GPa) and intrinsic strength (125 GPa) of graphene sheets,43 and these results indicate that PEGA composites could possess a higher wear resistance.44As shown in 4.δ) of 0.213 at room temperature and the temperature range of tan δ > 0.3 from 43.3 to 85.7 °C. PEGA-40 has tan δ value of 0.281 at room temperature and a temperature range of tan δ > 0.3 from 25.5 to 81.2 °C, which covers the usual applied temperature range. Thermal decomposition temperatures T10 (10% weight loss) of PEGA-20 and PEGA-40 increase by about 18.1 and 13.7 °C compared with those of corresponding PU/EP-20 and PU/EP-40. Furthermore, flexural strength, flexural modulus and Shore D hardness of composite PEGA-20 increased by approximately 45.1, 9.27 and 4.62%, respectively, while the values for PEGA-40 increased by 27.9, 89.3 and 6.45%%, respectively, when compared with those of corresponding PU/EP IPNs. The enhanced damping, thermal and mechanical properties of PEGA composites can be attributed to the uniform distribution of graphene sheets in the IPN matrix, which benefits from the three-dimensional interconnected porous network structure of graphene aerogel used and good interfacial adhesion at the nanofiller-matrix interface. It is expected that the PEGA composites can be used as good structural damping materials in future.In this study, polyurethane (PU)/epoxy (EP) interpenetrating polymer networks (IPNs) filled graphene aerogel (PEGA) were facilely fabricated by a one-step vacuum-assisted filling process. The effects of PU content on damping performance, thermal stability and mechanical properties of the PEGA composites were studied systematically. Composite PEGA-20 (weight ratio of PU/EP of 20/80) exhibits a damping loss factor (tan There are no conflicts to declare.RA-008-C8RA04718A-s001


BT at room temperature can be determinately achieved for trapping of a 10 nm Au sphere by optimizing the surface medium film layer of the designed graphene-hybridized Silica substrate. This is explained as the crucial role of graphene hybridization participating in plasmon enhancement for generating the highly localized electric field, in return augmenting the trapping force acting on the trapped sphere with a deepened potential well. This study can be helpful for designing the plasmon trapping of very small particles with new routes for molecular-scale applications for molecular-imaging, nano-sensing, and high-sensitive single-molecule spectroscopy, etc.We theoretically investigated the plasmon trapping stability of a molecular-scale Au sphere via designing Au nanotip antenna hybridized with a graphene sheet embedded Silica substrate. A hybrid plasmonic trapping model is self-consistently built, which considers the surface plasmon excitation in the graphene-hybridized tip-substrate system for supporting the scattering and gradient optical forces on the optical diffraction-limit broken nanoscale. It is revealed that the plasmon trapping properties, including plasmon optical force and potential well, can be unprecedentedly adjusted by applying a graphene sheet at proper Fermi energy with respect to the designed tip-substrate geometry. This shows that the plasmon potential well of 218 k In recent years, the plasmon trapping of nanoparticles with typical size of sub-100 nm less than light diffraction-limit has attracted great attention for both scientific and practical purposes. The plasmon trapping of molecular-scale nanoparticles can find a broad range of potential applications like molecular-imaging, nano-sensor, and single-molecule spectroscopy ,3,4,5. PTo date, a series of investigations on the optical trapping in contact with the tip of probe have been carried out ,20. A thBT at room temperature via optimizing the surface medium film layer of the graphene-hybridized Silica substrate system. The results are well explained as the crucial role of Au-graphene hybridization participating in generating a highly localized electric field for supporting the high-stable trapping process. This study would be helpful for understanding the stable plasmon trapping properties for molecular-scale targets for advancing the potential applications in fields of molecular-imaging, nano-sensing, and single-molecule spectroscopy, etc.In this paper, we perform theoretical investigations on improving the stability for plasmon trapping of molecular-scale Au nanosphere with diameter of 10 nm by designing graphene-hybridized tip-substrate system. A hybrid plasmonic trapping model is self-consistently built for comprehensive predictions of plasmon trapping properties on the optical diffraction-limit broken nanoscale. It is proposed that the plasmon trapping potential around the targeted Au nanosphere can be unprecedentedly achieved to be as high as 218 kz axis. In this case, the confinement of local surface plasmon mode can exhibit radial symmetry distribution in local space around the z axis. So, the 2-D modeling is qualified for revealing the full 3D space properties of plasmon trapping potential well. The optical force originating from the gradient and scattering localized electric field can be physically generated from the hybrid plasmon system as laser wavelength matches to surface plasmon resonance frequency, which is mainly determined by the graphene-functioned tip-substrate configurations. On the other hand, the resonance wavelength of the plasmon can be closely affected by the graphene plasmon dispersion relation [0 is polarizability of a point-like particle, E is incident electric field, n is index of refraction for surrounding medium, σ is total cross-section of the particle, c the speed of light, H the incident magnetic field, 0k the laser wave vector in free space. A 2-D hybrid plasmonic trapping model for the comprehensive predictions of plasmonic trapping properties is proposed, in which the nanotrapping geometry is made of an Au tip with a graphene sheet, which is embedded in between surface medium film and Silica substrate see . The Au relation ,29. The relation F=14ε0ReHere, we carefully consider the plasmonic optical forces exerting on Au sphere by building the self-consistent Helmholtz equation model integrated with optical forces calculations from three types of contribution of gradient forces, radiation pressure force, and polarization force. The gradient distribution of the localized electric field would play a crucial role in generating the plasmonic trapping force for the graphene-hybridized tip-substrate system. Namely, the gradient force facilitates spatial confinement in optical trapping dominance compared to the other two forces. Furthermore, the plasmon polarizability is a key factor that characterizes optical response due to the plasmonic interaction between the optical field and nanostructure that determines the strength of plasmonic optical trapping properties. The trapping potential resulting from the optical forces is a key factor that determines the stability of the optical trap, and it can be obtained by Ur0=∫∞r0Numerically, we firstly build hybrid geometry of the tip-substrate system, in which three layers graphene sheets with thickness of 1 nm are embedded in the substrate. Here, the graphene with respect to the Fermi energy modifications are modeled with the surface optical conductivity considering the intra and inter band contributions ,33. Then0| can achieve values as high as 240 at wavelength 4.65 μm by applying Fermi energy of 0.6 eV, as seen in 0| can be remarkably further elevated for an even higher Fermi energy of 0.8 eV. Simultaneously, the plasmon resonance wavelength obtains an obvious blue-shift from 8 μm to 4 μm. The scale law of resonance wavelength vs. Graphene Fermi energy as FE−1/2 for a given wavevector q typically appears in the current result, originating from the intrinsic interband contributions to static graphene screening, which can be effectively absorbed in a background dielectric constant [constant . Also, t6 V/m at the applied electric field amplitude of 5.5 × 104 V/m of the external laser excitation. Here, the external laser electric field amplitude is properly controlled to range from 3.5 × 104 V/m to 5.5 × 104 V/m in order to avoid laser local damage to the trapping system. It should be noticed that the localized electric field across the tip-sphere gap exhibits obvious large gradient distribution in cases of applying higher Fermi energy or larger electric field amplitude of external laser excitation. This indicates that the plasmon trapping process can be optimized by successfully designing the graphene-hybridized tip-substrate system, which can be very important for advancing a wide range of stable-controlled plasmon trapping applications.The 2-D images of localized electric-fields for the designed graphene-hybridized tip-substrate system with respect to Fermi energy of graphene sheet and external laser excitation are shown in 4 V/m to 5.5 × 104 V/m. The maximal potential well of 149 kBT can be achieved in proximity of tip vertex at the incident laser electric field of 5.5 × 105 V/m. This is attributed to the strong plasmon hybridization of Au-graphene in the tip-substrate system assisted by reinforcement of augmented excitation of the external laser. Interestingly, as an Au sphere is put in the tip-substrate system, the quarter-poles distribution characteristics of plasmon force around the Au sphere can be observed, as seen from 4 V/m to 5.5 × 104 V/m. It should be emphasized that the trapping wavelength which is centered at 4.65 μm here has nothing to do with the external laser electric field. In fact, the quarter poles symmetry of trapping force together with the deepened plasmon potential well would play an active role in achieving the possible high stability of plasmon trapping for the potential applications of high-sensitive molecular-imaging, sensing, and SERS spectroscopy, etc.The 2D images of plasmon potential well for the graphene-hybridized tip-substrate system and the trapping force exerted on an Au sphere with respect to the electric field amplitude of external laser excitation are shown in x direction for the graphene-hybridized tip-substrate system is shown in BT for graphene sheet Fermi energy of 0.3 eV and 0.45 eV. Here, T is taken as 300 K in room temperature. This indicates that the plasmon trapping process becomes more and more unstable as the trapping potential falls into the saturation regime for the moderate graphene sheet Fermi energy of 0.3 eV and 0.45 eV, respectively. The result can be attributed to the unique role of graphene-functioned surface plasmon hybridization of the tip-substrate system, in which the surface plasmon resonance of the tip-substrate system can be significantly modified by varying the graphene sheet Fermi energy via a possible method of static electric doping [x displacement of the nanosphere from the tip apex. However, the plasmon trapping force can be badly impaired as the Au nanosphere displaces far from the tip apex. The localized electric field enhancement for supporting the plasmon trapping force exhibits a similar tendency with respect to the transverse displacement of Au nanosphere, which provides a basic understanding of the plasmon trapping force adjustment with respect to the localized electric field modifications for successfully designing and optimizing the displacement process of plasmon trapping for a molecular scale nanosphere with high stability.The plasmon trapping potential well and trapping force with respect to tip-to-sphere gap and the Au nanosphere transverse displacement at c doping . The plaBT defined by the Brownian motion energy. Here, the maximal plasmon potential well can be elevated from 132 to 218 kBT via optimizing the index of refraction the surface medium film layer at a large value of 2.0 (see  2.0 see b. The reBT can be achieved in proximity of the tip vertex at the incident laser electric field of 5.5 × 105 V/m. This is attributed to the strong plasmon hybridization of Au-graphene in the tip-substrate system assisted by the reinforcement of augmented excitation of the external laser. This shows that the plasmon potential well can be predominantly achieved in a range of 132 to 218 kBT by optimizing the index of refraction for the surface medium film layer on graphene covered Silica-substrate. This result can be critically important for understanding the high-stable plasmon trapping ability based on the graphene-functioned tip-substrate system for advancing the molecular-scale applications of nanoimaging, nanosensing, and SERS spectroscopy, etc.We have theoretically investigated the achievable high-stability for plasmon trapping of Au nanosphere with a diameter of 10 nm by designing a graphene-hybridized Au-tip/Silica-substrate system. The localized electric field enhancement can achieve 240 by modifying the Fermi energy of the graphene sheet for the designed tip-substrate geometry. The maximal potential well of 149 k


Although two-dimensional (2D) materials have grown into an extended family that accommodates hundreds of members and have demonstrated promising advantages in many fields, their practical applications are still hindered by the lack of scalable high-yield production of monolayer products. Here, we show that scalable production of monolayer nanosheets can be achieved by a facile ball-milling exfoliation method with the assistance of viscous polyethyleneimine (PEI) liquid. As a demonstration, graphite is effectively exfoliated into graphene nanosheets, achieving a high monolayer percentage of 97.9% at a yield of 78.3%. The universality of this technique is also proven by successfully exfoliating other types of representative layered materials with different structures, such as carbon nitride, covalent organic framework, zeolitic imidazolate framework and hexagonal boron nitride. This scalable exfoliation technique for monolayer nanosheets could catalyze the synthesis and industrialization of 2D nanosheet materials. Top-down exfoliation is one of the most promising approaches for the scalable production of 2D materials, but the current techniques are limited by low yield of monolayers. Here, the authors report the exfoliation of graphene and other layered materials via viscous-polymer-assisted ball-milling, leading to a production of graphene products with monolayer percentage up to 97.9% at a yield of 78.3%. Although a number of monolayer 2D nanosheets have been achieved via bottom-up synthesis and chemical exfoliation methods, they are either restricted to a limited scale or introducing a large number of defects that impeded their applications7. Due to great scalability and mild processing conditions, mechanical exfoliation shows the potential for achieving a scalable production of high-quality 2D nanosheets. Plenty of mechanical exfoliation techniques, e.g., ultrasonication9, high-speed mixing10, and ball milling11, have been explored for the exfoliation of layered materials in liquid medium. Nanosheet products of these exfoliation methods, however, are predominantly thick multi-layer nanoflakes. The monolayer-nanosheet percentage in these products is often less than ~20%10.Scalable production of monolayer 2D materials with minimized defects and much preserved pristine properties of their bulk counterparts are critical in many applications12. It has been proven that simply enhancing shear rate  unfortunately has limited improvements on exfoliation in term of yield and monolayer percentage14. To achieve effective exfoliation, shear force in liquids must be effectively transferred to the targeted materials. Nonetheless, the force transfer in current LPE methods is insufficient because of the low viscosity of commonly used solvents15. More recently, dry-state ball-milling using solid diluents has been explored as an alternative to LPE. Although enhanced exfoliation yield was achieved due to the high force transfer efficiency of solid diluents, the obtained 2D nanosheet products possess broad thickness distribution and small lateral size due to intensive crushing coupled with shearing during dry-state mixing17.The failure of producing monolayer nanosheets at high yields by current liquid phase mechanical exfoliation (LPE) is thought to be the result of insufficient delamination force applied on layered materials20, herein, we introduce a technique called sticky mechanical exfoliation by applying liquid polymer as an exfoliation medium in ball-milling method to achieve a scalable production of monolayer nanosheets based on two main interlocked criteria: (1) Exfoliation medium should possess a high viscosity to facilitate shear force transmission; (2) Exfoliation medium should have a strong adsorption energy on common layered materials to stick on the layered material during delamination process. Preliminary screening experiments shows that high-viscosity, branched polyethyleneimine (PEI) is an appropriate candidate. With the assistance of PEI, graphite and other four types of representative layered materials with different structures including, carbon nitride, covalent organic framework, zeolitic imidazolate framework, and hexagonal boron nitride, are effectively exfoliated into monolayer nanosheets at high yields.Inspired by the well-known scotch-tape exfoliation21. The graphene powder samples (freeze-dried from rinsed water solution) show broad peaks (100)/(101) at 43–45° and (110) at ~76°, corresponding to the 2D in-plane symmetry along graphene sheet. The decreased intensity of these peaks indicates the decreased lateral size with prolonging the milling time. All powder samples show a weak peak (002) at ~26°, a characteristic of paralleled graphene layers, which could mainly arise from nanosheet re-stacking during sample drying process.The feasibility of this technique was first exemplified by graphite exfoliation. In a typical operation, graphite and PEI were mixed in milling jars and milled at 500 rpm for 5–15 h, and exfoliated products were collected and dispersed in water. The dispersion was then repeatedly rinsed with water on a homemade filtration device to remove free PEI molecules  and reduced GO (rGO) (~0.7–0.9)24, indicating the much preserved high-quality lattice of the as-prepared graphene nanosheets. Transmission electron microscopy (TEM) characterization also shows that these graphene nanosheets have lateral sizes of hundreds of nanometers, in agreement with AFM characterization. The weak contrast of these nanosheets to TEM carbon grid reveals that they are ultrathin. As illustrated in Fig. 25, providing further evidences that the as-exfoliated products are dominated by monolayer graphene.When rinsed graphene solution was deposited on mica, plenty of small flat disks with a lateral size of hundreds of nanometers and a height between 0.5 to 1 nm were observed Fig. . In addine8 Fig. . In addiA statistical analysis on the AFM height profiles of over 200 graphene nanosheets (after 10 h milling) shows that 91.2% of the nanosheets are monolayered and their lateral sizes are averaged at 780 nm Fig. . More im10, the excellent re-dispersibility of the graphene nanosheets synthesized via this sticky milling offers crucial convenience in practical transport, storage, and processing. We believe that the excellent re-dispersibility of the graphene nanosheets is attributed to a small amount of residual PEI on graphene nanosheets. Elemental analysis, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) analysis revealed that the weight percentage of residual PEI on the graphene nanosheets is in the range of 6.3–12.4 wt%  Fig. . Graphenwt% Fig. , 4.2. Th−1, corresponding to a conductivity of ~28,000 S/m. The conductivity was further promoted to ~322,000 S/m by removing residual PEI 30. In addition, due to the presence of residual PEI, the as-prepared graphene nanosheets are highly positively charged with a zeta potential of up to +52.9 mV at pH of ~6  at a rate up to 3.8 mol m−2 h−1 while a relatively low transport rate of divalent ions , leading to a competitive mono/divalent ion selectivity of 5.11–7.0  than that of nanosheets from sonication exfoliation strategies with sharp edges9.The in-plane breaking of graphite occurs when sufficient compression force is applied following the random collisions between grinding balls. Statistical analysis on this force shows that the compression force is in the range of 0 to 2 N Fig. , which i µm Fig. . The sha µm Fig. . In stic 37 Fig. . PEI mac 37 Fig. . Since t 37 Fig.  as well V) can be transferred to strong shear force to enable the sliding of neighboring layers. Interestingly, the required shearing force for the dislocation of adjacent layers is highly direction-dependent. The preferential sliding direction is the zigzag direction with a maximum required shearing strength of 0.116 GPa, which is only a third of the required shearing strength (0.342 GPa) when sliding along the armchair direction ), and materials strongly held via intense polarized interaction ). DFT calculation indicates the applicability of this sticky milling to the exfoliation of these materials from two key aspects. On one hand, the highest shearing strength along the preferential sliding direction of these materials still locates at the same magnitude as that of graphene, ranging from 0.01 to 0.190 GPa and following the sequence of COF < Graphene < g-C3N4 < h-BN , zeolitic imidazolate framework (ZIF-L), porous graphitic carbon nitride  with average Mn at ~10,000 by GPC, average Mw at ~25,000 by Light scattering (LS)   was applied as a modifier to assist exfoliation. In order to assess the crucial role of high viscosity, low-molecular weight branched PEI with average Mw at ~800 by LS   was chosen to mix with h-PEI at various ratios, giving PEI modifiers with viscosity at different levels, covering the range from 1508 to 150,882 mPa·s measured at ~20 °C  were used in this work. In a typical exfoliation process, pristine layered crystals (0.5 g) and 2 g PEI (high-viscosity PEI was used in most experiments unless stated) were loaded into 250 mL milling jars. The milling jars was loaded in a planetary ball mill  with its revolution radius at 10 cm and rotation radius equal to the radius of the milling jar at 39 mm. The rotation speed was set as 250 rpm for revolution and 500 rpm for rotation. Other parameters are listed in Supplementary Table ZrO3N4, ZIF-L and TAPB-PDA COF can be found in Supplementary Section The rinsing process of graphene/PEI mixtures is described in Supplementary Section Supplementary informationPeer Review File


Insulated gate bipolar transistor (IGBT) is an important power device for the conversion, control, and transmission of semiconductor power, and is used in various industrial fields. The IGBT module currently uses silicone gel as an insulating layer. Since higher power density and more severe temperature applications have become the trend according to the development of electronic device industry, insulating materials with improved heat resistance and insulation performances should be developed. In this study, we intended to synthesize a new insulating material with enhanced thermal stability and reduced thermal conductivity. Poly(imide-siloxane) (PIS) was prepared and crosslinked through a hydrosilylation reaction to obtain a semi-solid Crosslinked PIS. Thermal decomposition temperature, thermal conductivity, optical transparency, dielectric constant, and rheological property of the Crosslinked PIS were investigated and compared to those of a commercial silicone gel. The Crosslinked PIS showed high thermal stability and low thermal conductivity, along with other desirable properties, and so could be useful as an IGBT-insulating material. The insulated gate bipolar transistor (IGBT) is a device for the conversion, control, and transmission of semiconductor power, and is used in various industrial fields such as automobiles, aviation, and home appliances ,2,3. AccSilicone gels are generally used for insulating high voltage multichip power assemblies for their high softness and insulating properties ,5. The gPolyimides have advantageous properties such as good mechanical properties, thermal stability, and chemical resistance ,15,16,17In this work, we first developed a new PIS gel for application as an insulating material for IGBT. A PIS was prepared and crosslinked through a hydrosilylation reaction to obtain a semi-solid Crosslinked PIS. Thermal stability, thermal conductivity, optical transparency, dielectric constant, and rheological property of the Crosslinked PIS were investigated and compared to those of the commercial silicone gel.n ~3000) and trimethylsiloxy-terminated methylhydrosiloxane-dimethylsiloxane (MHS-PDMS) copolymers (MHS unit mole % = 0.5–1.5) were purchased from Gelest . Tetrahydrofuran (THF) and methanol were purchased from Samchun Chemicals , distilled from N2/benzophenone, and stored under nitrogen atmosphere. Pyridine was purchased from Alfa Aesar Chemicals . Acetic anhydride was purchased from Junsei Chemical Co., Ltd. . A commercial IGBT module was purchased from I.G. International  and its insulating material was characterized. It is considered that the insulating material is a PDMS-based gel  because its IR spectrum is practically the same as that of an authentic PDMS diphthalic anhydride (6FDA), allyl isocyanate, and platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution (in xylene) were purchased from Sigma-Aldrich Korea . Bis(3-aminopropyl)-terminated polydimethylsiloxane (PDMS)  spectra of samples dissolved in CDCl3 were acquired using a Bruker Avance II 400 MHz spectrometer . Gel permeation chromatography (GPC) was carried out using a chromatographic system  in refractive index mode. The GPC was conducted using a doubly connected Showa Denko Shodex KF-806L column at 40 °C and THF as an eluent at a flow rate of 1.0 mL/min, and the results were calibrated with respect to polystyrene standards. In the GPC analysis, the number average molecular weight (n), weight average molecular weight (w), and polydispersity index (PDI) were measured. Thermal analyses were carried out under a nitrogen atmosphere with a balance flow rate of 40 mL/min and a furnace flow rate of 60 mL/min using a Discovery TGA 55  at a heating rate of 10 °C/min. Thermal conductivities (in-plane) of the samples were measured using a LFA 467 Nanoflash  at 25 °C under a nitrogen atmosphere. Elemental analysis was carried out using a Flash 2000 . Ultraviolet–visible spectroscopy was carried out using a Lamda 25 UV/Vis spectrometer . Dielectric spectroscopy was performed using a E4980A dielectric spectrometer  at 22 °C in the frequency range of 50–1,000,000 Hz. The rheological property was studied using an Advanced Rheometric Expansion System .The drying and thermal treatment of samples were conducted with a vacuum oven . Fourier Transform Infrared (FT-IR) spectroscopy was carried out using a Spectrum One B FT-IR spectrometer  using the KBr pellet technique with the following scan parameters: scan range 400–4000 cm−1 (C=O stretching of carboxyl), 1640 cm−1 (C=O stretching of amide), 1260 cm−1 (symmetric deformation of -CH3 group in -Si(CH3)2-), 1092 and 1021 cm−1 (Si-O-Si stretching), 802 cm−1 (Si-C stretching).Poly(amic acid-siloxane) (PAAS) was prepared using a molar ratio of 6FDA:PDMS of 1:1.05 . Firstly−1 (imide C=O asymmetric stretching), 1726 cm−1 (imide C=O symmetric stretching), 1363 cm−1 (imide C-N stretching), 1260 cm−1 (symmetric deformation of -CH3 group in -Si(CH3)2-), 1092 and 1021 cm−1 (Si-O-Si stretching), 802 cm−1 (Si-C stretching). 1H NMR  H: 0.05 , 0.53–0.58 , 1.68–1.70 , 3.64–3.68 , 7.74–7.89 . Anal. Calcd: C, 36.34; H, 7.48; N, 0.82. Found: C, 36.31; H, 7.68; N, 0.86.The preparation of PIS is illustrated in 1H NMR  H: 0.05 , 0.53–0.58 , 1.64–1.72 , 3.64–3.68 , 4.28–4.29 , 5.18–5.27 , 5.81–5.89 , 7.74–7.89 .The preparation of Allyl-PIS is illustrated in The crosslinking reaction of Allyl-PIS was performed to synthesize a Crosslinked PIS gel material . The croAs illustrated in −1 (carboxyl) and 1640 cm−1 (amide), owing to C=O stretching. The absorption bands at 1021 and 1092 cm−1 are due to the stretching vibration of the Si-O-Si group in the PDMS structure, and the absorption band at 1260 cm−1 is attributed to the symmetrical deformation of the -CH3 group in the -Si(CH3)2- group. The absorption band at 802 cm−1 corresponds to Si-C vibration [−1 due to imide C=O asymmetric stretching, at 1726 cm−1 due to imide C=O symmetrical stretching, and at 1363 cm−1 due to C–N stretching were observed. The absorption bands of the PDMS structure described above were also observed in the PIS spectrum.As shown in ibration ,32,33,341H NMR spectroscopy and elemental analysis. In the NMR spectrum of PIS (3) in the PDMS unit was identified (0.05 ppm). In addition, three methylene group (-CH2-) peaks at both ends of the PDMS were identified  and proton peaks in the aromatic ring were observed at 7.74–7.89 ppm. In the elemental analysis of PIS, the calculated values of C, H, and N were 36.34%, 7.48%, and 0.82%, respectively, and the measured values were 36.31%, 7.68%, and 0.86%, respectively, indicating good agreement between the calculated and measured values.The structure of PIS was also confirmed by m of PIS , the pea1H NMR spectroscopy. The FT-IR spectrum of Allyl-PIS was practically the same as that of PIS (1H NMR spectrum of Allyl-PIS (3) in the PDMS unit was identified (0.05 ppm). In addition, three methylene group (-CH2-) peaks at both ends of the PDMS were identified . Allyl proton peaks were identified  and proton peaks in the aromatic ring were identified (7.74–7.89 ppm).The preparation of Allyl-PIS is illustrated in t of PIS . In the llyl-PIS , the peaThe synthesized Allyl-PIS was crosslinked through the hydrosilylation reaction between Si-H and allyl groups to obtain Crosslinked PIS as a semi-solid product. Allyl-PIS was reacted in the presence of the crosslinker (MHS-PDMS) and catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution) using reaction mixtures with various compositions. During the crosslinking reactions, the reaction mixtures showed a tendency to foam, probably due to the evaporation of residual solvents. Foaming may cause the nonuniformity of properties, decrease in mechanical properties, and optical opacity. On the other hand, since the PIS rapidly converted to a dark brown substance above 150 °C, the reaction was performed at 140 °C or below. However, when the reaction mixtures were directly heated up to 140 °C, foaming inside the products occurred. In order to avoid foaming, the reaction was conducted by stepwise heating under vacuum. The reaction was first performed at 40 °C overnight and then at 70 °C, 100 °C and 120 °C for 1 h each, and finally at 140 °C for 3 h. The composition of the reaction mixtures and state of the products are summarized in We attempted to find the optimum reaction composition to give non-foamed semi-solid . The sofNext, the concentration of the crosslinker was fixed at 3 wt%, and then the crosslinking reactions were performed by varying the concentration of the catalyst (0.1 or 2 wt%) (Run No. 9 and 10 in −1) would reduce as the reaction between Si-H and allyl groups proceeds [−1) of a mixture sample after each stepwise heating was compared with that of the sample before heating. The remaining percent of the Si-H groups was determined to be 91%, 80%, 53%, and 17% after stepwise heating at 40 °C, 70 °C, 100 °C, and 120 °C for 1 h each, respectively (The progress of the crosslinking reaction of the mixture having the Run No. 2 composition was investigated by FT-IR spectroscopy . It was proceeds . As showectively . The rem5 and T10) of the Crosslinked PIS   was conducted to study thermal decomposition temperatures (Tnked PIS . T5 and  422 °C) . This rek) of the Crosslinked PIS and commercial gel was investigated by the laser flash method (LFA) at room temperature (25 °C). The k value can be calculated using the equation k = α × ρ × Cp, where α is thermal diffusivity; ρ, measured density; and Cp, specific heat capacity. The k value of the Crosslinked PIS was determined to be 0.11 W/m·K  than PDMS (k = 0.25 W/m·K) [3 groups leads to an increase in free volume, further lowering the thermal conductivity [The thermal conductivity of a transistor insulating material is required to be low because the heat conduction between electronic devices should be minimal. Thermal conductivity  . It was uctivity ,38. The 3 groups in the PIS, which prohibits the formation of charge-transfer complexes by sterically repelling adjacent chains [IGBT modules may undergo partial discharge, and optical detection of the possible problem is sometimes carried out. Therefore, their insulating layer needs to be transparent ,40. A pht chains . For comt chains .Low dielectric constant is one of the important properties for insulating materials in electronic devices . The dieViscoelastic measurements of Crosslinked PIS and the commercial silicone gel were carried out using a rheometer . The fre5 and T10 values of the Crosslinked PIS were 416 °C and 454 °C and those of the silicone gel were 378 °C and 422 °C, respectively, indicating higher thermal stability of Crosslinked PIS than the silicone gel. The thermal conductivity value of Crosslinked PIS was 0.11 W/m·K, which was much lower than that of the silicone gel (0.19 W/m·K). The higher thermal stability and lower thermal conductivity of the Crosslinked PIS could be achieved by incorporating the imide ring structure into a PDMS-based structure. Besides, the dielectric constant of the Crosslinked PIS was 3.11, which means that it is a low dielectric material. Crosslinked PIS showed a high optical transmittance of over 90% at 550 nm, allowing for the optical detection of a possible problem of the material. The elasticity of the crosslinked PIS was higher than the viscosity, which means that Crosslinked PIS is a polymer gel. Based on these properties, the Crosslinked PIS may be useful as an insulating layer of IGBT.PIS was synthesized from 6FDA and PDMS, and its end groups were modified using allyl isocyanate. The resultant Allyl-PIS was crosslinked by the hydrosilylation reaction in the presence of the crosslinker and Pt catalyst. The properties of the Crosslinked PIS were investigated and compared to those of the commercial silicone gel. T


This study aimed to create and validate an instrument to measure pediatric residents’ knowledge about development and behavior.This was a longitudinal study with the consecutive application of questionnaires to validate an instrument of analysis. The modified Delphi technique was used for validation, which involved judges who were selected based on their expertise. Judges, who were renowned for their knowledge of the subject and willing to participate, were chosen from different states of Brazil. A convenience sample was obtained. The original questionnaire included 45 open questions divided into 13 relevant thematic axes on development and behavior.After the third round using the Delphi technique, the whole questionnaire had a validity index of more than 80% on scope and relevance as well as all thematic axes, and the 44 final questions.The whole questionnaire was considered validated by the 14 expert judges who participated in the study. The cognitive and socioemotional skills developed during this time will impact academic achievement, health, and general well-being in adulthood.The first 5 years of a child's life is the period when the developing brain is most susceptible to stimulation.Despite affecting millions of children worldwide, developmental disorders are under diagnosed and there is a significant lack of available studies, especially in developing countries. Despite the significant number of cases, most children remain undiagnosed and, subsequently, untreated. Pediatricians identify only 50% of cases before children begin preschool.According to studies conducted in the United States, it is estimated that at least one in five children present with either developmental and/or behavioral disorders.Early diagnosis is important for timely intervention, with better long-term outcomes. The child's general pediatrician should be the professional responsible for surveillance. For a subject so prevalent in the pediatric environment, and with such significant impact on individual and collective health, the emphasis given in our pediatric medical residency programs is low. In contrast, one of the concerns of medical educators is guaranteeing the teaching quality of the residents. One of the ways of reaching this is using competency assessment methods.In Brazil, the National Board of Medical Residency requires the study of this subject in its accredited programs but does not stipulate minimum credit requirements.Considering that the pediatrician is the professional who would diagnose these disorders, we justified the elaboration of this project. We hypothesized that a validated questionnaire would successfully measure pediatric residents’ knowledge and ability to diagnose developmental and behavioral disorders. Our theoretical framework is that a questionnaire could identify knowledge gaps in residents. Thus, we aimed to build and validate an instrument to assess the knowledge regarding the diagnosis of behavior and development disorders.We used a consecutive application of questions to validate an instrument of analysis based on validation techniques. The method used to consult specialists was the modified Delphi technique.We obtained validation by submitting questionnaires to a group of judges:Physicians with medical residency in pediatrics or child neurology and/or with a title of specialist in child neurology;With at least 3 years of working experience in the field of pediatric development.Judges, who were renowned for their knowledge of the subject and willing to participate, were chosen from different states of Brazil. We used a convenience sample, predominantly using specialists recommended by the Brazilian Society of Child Neurology, prioritizing those with the most titles. We stipulated a minimum of 10 judges for the first round of this study, according to the sample size calculation to obtain validity.We sent each selected judge an electronic invitation stating the project's objectives and an Informed Consent Form. Those judges who agreed to participate in the study received the instrument via Google Forms, an online data collection tool.Judges received questionnaires containing:Expert/Specialist Characterization Data and45 multiple choice questions, each with 4 multiple choice alternatives in which only one option was correct, distributed across 13 thematic axes.We used a 4-point Likert scale, ranging from 1  to 4 , in order to gauge the opinion of the experts. We evaluated questions, thematic axes, and the questionnaire as a whole. in addition to important scientific articles. The questionnaire is available by request with the corresponding author.The initial questionnaire, containing 45 questions, with 4 multiple choice alternatives each, and distributed across 13 thematic axes, was elaborated with emphasis on diagnosis. We based this questionnaire on the areas of greatest importance within the subject, using two main bibliographic references ,The preparation of the questionnaire followed guideline recommendations for the preparation of multiple choice tests.A single researcher elaborated the questions using the aforementioned bibliography and taking into account all the cares as listed above. The researcher responsible for the idealization and construction of the questions had a degree in general pediatrics.The 13 thematic axes were chosen based on relevance within the subject in question and literature thereof, and are as follows:Screening and surveillance of developmental and behavioral disorders, recognition of normal development, and warning signs regarding developmental delays;Intellectual disability;Specific learning disorders, including major differential diagnoses such as dyslexia, dyscalculia, and dysgraphia;Secondary learning disorders due to visual and auditory difficulties, organic diseases, and/or abuse and ill treatment;Follow-up of high-risk newborns;Excessive crying of infants;Sleep disorders;Speech and language disorders;Eating disorders;Anxiety and depression;Temperament and disruptive behavior;Autism spectrum disorders; andAttention deficit hyperactivity disorder.We measured the Content Validity Index (CVI) and we expected to obtain a CVI greater than 0.8 (or 80%) to finish the current round of the Delphi technique and thus consider the questionnaire validated. with ordinal weight, and the coefficients were accompanied by intervals of 95% confidence and p-values. We compared the coefficients of agreement to the classification present in Altman, which considers the following: “poor” coefficients lower than 0.2, “reasonable” those between 0.2 and 0.4, “moderate” those between 0.4 and 0.6, “good” between 0.6 and 0.8, and “excellent” those above 0.8.We evaluated the agreement between the judges using a coefficient of agreement appropriate to the distribution of responses, such as Gwet's AC2,The Research Ethics Board of the Hospital Israelita Albert Einstein approved this study under the registration number 2.955.041 dated October 10, 2018.We invited a total of 37 specialists to participate in the project. Of these, 17 declined participation, and 6 did not respond to the invitation.A total of 14 specialists, aged 31–66 years, equally divided between men and women, participated in the study – the mean time since their graduation was 22 years, ranging from 6 to 43 years. The majority of specialists (10/14) practiced child neurology. Of the 14 participants, 6 had at least 15 years of working experience in the field of study, and 9 had at least a master's degree. Of the 45 questions submitted in the first round, 17 presented a CVI below 0.8 requiring reformulation. Of the 13 axes, 4 did not obtain satisfactory CVI for relevance and/or comprehensiveness, and the questionnaire, as a whole, did not present sufficient relevance. After the statistical analysis of the 17 questions, we eliminated 6 with CVI below 0.8 due to structural errors, reformulated 11, and inserted 6 new questions. In addition, the 20 questions that obtained satisfactory CVI in the first round underwent minor changes, as suggested in the open field by the experts.In the second round, 10 of the original 14 specialists participated in the evaluation of the instrument. We evaluated a total of 31 question reformulations, in addition to the 6 new questions, the scope of axes 1, 2, and 6, the relevance and scope of axis 8, and the questionnaire as a whole.Only three questions did not obtain the necessary CVI after the second round. After the modifications, axes 1, 2, 6, and 8 presented sufficient coverage, and axis 8 also showed sufficient relevance. Regarding the evaluation of the total questionnaire, 100% of the participating experts agreed or fully agreed with the questionnaire's relevance and scope.In the third round, 9 of the original 14 specialists participated in the evaluation of the instrument. We asked experts if they agreed to the small changes made to the already satisfactory questions, and six (66.7%) agreed to all the amendments.We also evaluated the reformulations of three questions. Only one question obtained indexes lower than 0.8 for clarity in the statement, clarity in the alternatives, and coherence between statement and answer. By presenting such a result, we removed this question from the final version of the instrument.The final instrument consisted of 45 questions, all with satisfactory CVIs, with the lowest observed value of 0.8 (80%).The mean CVI for the instrument is 0.954 (95.4%).  with ordinal weights, given the nature of the response categories  and the concentration of answers were in the two highest categories . The coefficients were accompanied by 95% confidence intervals and p-values for the equality hypothesis test to zero. The coefficients show good or excellent agreement according to the criterion proposed by Altman, with the lowest coefficient of 0.792, observed for the scope of the questionnaire as a whole and of the individual axes, and the higher coefficient of 0.926 observed for relevance and relevance of the questions. After we completed the third round, we evaluated the agreement between the judges using Gwet's AC2 Coefficient of AgreementWe submitted the final instrument to a Portuguese teacher for orthographic analysis.After the third round of the Delphi technique, we validated a total of 44 questions. As of the second round, all axes and the whole questionnaire had CVI higher than 0.8 (80%) in scope and relevance.  The mean CVI of the instrument was high 0.95 (95%), and the overall coefficient of agreement of 0.89 and p-value lower than 0.001.The present study used psychometrics and CVIs to validate a questionnaire created to assess a resident's knowledge of developmental and behavioral disorders. We stipulated a CVI of 0.8 to validate questions, axes, and questionnaire as a whole. For this, it was necessary to conduct three rounds of the Delphi technique. Despite the stipulated cutoff point of 0.8, the CVI of 89% of the questions was higher than 0.9. The CVI regarding the questionnaire's relevance and axes was also higher than 0.9, and we had only four axes with CVI ranging from 0.8 to 0.9.The coefficient of agreement was also high, reaching 0.89 in the overall analysis. The coefficient of agreement was lower for the scope of the axes and questionnaire, which can be explained by the immense amount of content existing in the field of development and behavior. the greatest importance is not in the number of participating judges but quality and representativeness. We consider the sample of judges satisfactory both because they meet the inclusion criteria and because they come from different regions of the country.Initially, the minimum number of judges considered was 10 specialists. However, we were able to obtain the participation of 14 specialists for the first phase. Only 37% of 37 specialists accepted our invitation, justified by the amount of time required to evaluate the questionnaire. According to the literature,Despite the widespread presence and overarching impacts of developmental and behavioral disorders, some reasons do justify the difficulties experienced by the general pediatricians diagnosing problems on the frontlines: first, general pediatricians lack the preparation to diagnose and monitor these children; second, there is a shortage of sufficient time for pediatric consultations, a lack of validated screening instruments in Brazil, and professionals lack the necessary training to use these instruments; finally, we emphasize the extremely small number of professionals, multidisciplinary teams, and development and behavior specialized services throughout the country. In addition to the issues mentioned above, there are no mandatory course-load minimums (minimum credit requirements) stipulated by the National Commission of Medical Residency in Brazil.When validated, we expect that the medical community would consider this questionnaire a reliable tool for evaluating residents’ knowledge on the subject and serve as a means of diagnosing possible training deficits of the pediatricians in question. This instrument will be applied to the evaluation of residents in a future study. The validated instrument can be found in the annexes.The strengths of this study include the widespread geographical distribution of specialists and their representativeness, the higher-than-expected sample size, the validation of the questionnaire with high CVIs already shown in the second round of the Delphi technique, and, finally, the use of the coefficient of agreement as one of the reliability measures.As for the study's limitations, we cite that the evaluation of this field of study through multiple choice questions, although practical, may not cover all the peculiarities and details. We must also mention the absence of a pilot test to evaluate other aspects of reliability and the power to discriminate questions.Another limitation was the lack of interaction between the members of expert's panel. The dialogue is an important factor for reaching a consensus. However, operational limitations have made the process impracticable.In conclusion, we constructed a questionnaire to assess knowledge in diagnosing developmental and behavioral disorders. With CVI greater than 0.8 and high agreement of the 14 specialist judges, we consider the 44 questions, all 13 axes, and the questionnaire as a whole validated. Thus, we consider the questionnaire sufficiently relevant and comprehensive to evaluate residents’ knowledge regarding the diagnosis of developmental and behavioral disorders.


Additionally, the distribution of the electric field and the propagation of the magnetic field for resonant and non-resonant conditions of the proposed structure were illustrated. It was found that an enhanced field was exhibited on the surface of the plasmonic material for resonant conditions. We also measured the penetration depth of 180 nm using decayed electric field intensity. Furthermore, the impact of using a 2) of 0.9858. Finally, numerical results obtained in this manuscript exhibited high sensitivity in comparison with previously reported studies.In this article, a hybrid  Recently, cancer has become one of the main causes of mortality all over the world. Nearly 10 million deaths are caused worldwide due to cancer, according to the World Health Organization (WHO) . Cancer Biosensor technology is a flourishing field to fulfill the need for sensitive and rapid detection problems . At firs2 structure-based cancer detection method recently, but the reported sensitivity is only 185 deg/RIU, whereas our proposed sensor exhibits 58% higher angular sensitivity. Although several other optical cancer detections process has been proposed, angular SPR-based detection is a more sensitive and much less complex structure to fabricate.At present, for cancer detection, a number of optical fiber sensors based on surface plasmon resonance (SPR) have been developed due to their portability, compactness, and better sensing performance ,26,27,28In recent times, the enormous enhancements in the fabrication technology and the sensitivity of the SPR-based prism-coupled Kretschmann configuration sensors have remarkably improved. Additionally, having a graphene layer on the sensing medium exhibits both excellent conductivity and the ability to stably absorb biomolecules. The main reason behind the absorption of a biomolecule with a graphene layer is the carbon-based rings that widely exist in biomolecules. In addition to having a special molecular structure, the p-stacking interactions between graphene hexagonal cells and carbon-based ring structures are widely present in bio/nanomolecules ,39. Due 7/−1, 48.02 RIU−1, and 3.84, respectively.In this paper, the main aims are to determine the refractive index changes in cancer cells for early cancer detection purposes. For this reason, the design and analysis of a BKThe proposed guration . The fole laser) . Table 1e (CMOS) . For cal follows .(1)nBk72) was used as an adhesion thin film to provide strong interaction between the prism and plasmonic metal layer and enhance the refractive index sensitivity due to its high refractive index and good chemical stability [For the second layer, titanium dioxide nAu=The refractive index of graphene for the incident wavelength 3+i× 0.34 nm ,55. Fina 0.34 nm ,57,58. T 0.34 nm . Althoug 0.34 nm . Liquid  0.34 nm ,61,62,63The p-polarized or TM-polarized light reflectance intensity measurement is crucial for the sensing purpose of the SPR sensor. Surface plasmon waves (SPWs) are transverse waves with an oscillating electric field normal to the surface. The transverse magnetic polarization TM state describes how the surface plasmon spreads as an electromagnetic wave parallel to the x direction with a magnetic field orientated parallel to the y direction. Since surface plasmons only have an electric field component, which is normal to the surface, therefore, the initial prerequisite for SP excitation is the condition of the TM polarization state, which is required to produce the distribution of charges on the metal contact and to satisfy the boundary conditions necessary to excite SPR detailed in ,65. The Here,  follows ,67:(6)MiHere, the arbitrary phase constant is  follows ,66,68:, the figure of merits (FOM), and detection accuracy (DA) . The pro follows :(12)S=ΔθFurthermore, the signal-to-noise ratio (SNR) of the real SPR sensing system critically depends on how well one measures the signals with real instruments. It was calculated as follows ,69:(15)S−1, 48.02 RIU−1, and 3.84, respectively, and the full-width half maxima (FWHM) was found to be 3.8 deg. Finally, using Equations (13)–(15), the overall sensor parameters of detection accuracy (DA), the figure of merits (FOM), and signal-to-noise ratio (SNR) were found to be 0.263 deg7. Again, the Floquent periodicity periodic boundary conditions -based numerical simulation. To simulate the proposed model, COMSOL Multiphysics version 5.5 was utilized, and we simulated the 2D geometry of the proposed sensor. The structure of the proposed . Periodic boundary conditions (PBCs) are a set of boundary conditions that are often chosen for approximating a large (infinite) system by using a small part called a unit cell. PBCs are often used in computer simulations and mathematical models. Therefore, no effect of changing the width of the sensor was found; this was also simulated for widths of 1 and 1.5 thors of  demonstr2-based structure exhibits a PD of 150 nm [To further confirm the strong SPR excitation of the proposed /e (37%) ,73. Simi7 must be chosen as a substrate, and the sol-gel spin method would be used to deposit a thin layer of TiO2 on the prism’s base. Isopropyl titanate and isopropyl alcohol would be combined to create the solution for this usage [4) gas would be used as a carbon source [2SO4), the Cu foil would have to be removed. After the transfer of the graphene film by applying acetone ((CH3)2CO), the PMMA layer would be removed [This paper proposed and analyzed a hybrid is usage ,75. Thenis usage . In a chn source ,79,80,81 removed .7/Au/analyte structure. The simulation results demonstrated that, when using only the Au layer, the angular sensitivity of the detection of skin , cervical (HeLa), adrenal gland (PC12), and blood (Jurkat) cancer cells remains much lower compared to the proposed biosensor structure. In this section, the significance and impact of each deposited material layer for the detection of cancer are demonstrated. The sensitivity comparison of the influence of different layers is outlined in 7/Au/graphene/analyte structure. The results demonstrate that, when using graphene with Au, the sensitivity of the detection of skin , cervical (HeLa), adrenal gland (PC12), and blood (Jurkat) cancer cells increased compared to the results of only the Au layer. However, using only graphene with gold (Au) does not exhibit values as high as the proposed biosensor structure. Therefore, applying the TiO2 underneath Au enhances the sensitivity of detection of skin , cervical (HeLa), adrenal gland (PC12), and blood (Jurkat) cancer cells. However, the proposed sensor exhibits less sensitivity for breast (MCF-7) cancer cell detection compared with only Au and Au/graphene layers. However, the proposed BK7/TiO2/Au/graphene/analyte structure exhibits overall high sensitivity for all cancer cell type detection compared to only Au and Au/Graphene structures. Hence, the proposed BK7/TiO2/Au/graphene/analyte biosensor structure is used in this paper for the various types of cancer detection due to its high overall sensitivity for each cancer type.Similarly, to assess the impact of adding graphene, a simulation was undertaken for the BK7/TiO2/Au/graphene for cancer detection, where the thickness of the gold layer is taken to be 50 nm. In this section, we demonstrate the effects of the 50 nm gold layer on the various types of cancer detection. To verify the influence of the 50 nm thick gold layer, we varied the gold layer thickness, using thicknesses of 45 nm, 50 nm, and 55 nm within the proposed structure. The results of the angular sensitivity change regarding the assessment of Au layer thickness are tabulated in In this paper, we propose a biosensor structure of BKp is the prism refractive index; the real part of the metal-dielectric constant is represented by a.Here, nEach graphene layer sheet thickness can be denoted as r number . An anal7/TiO2/Au/graphene/analyte structured biosensor is demonstrated in this section. When a normal cell is affected by cancer, the refractive index of the cell increases. The refractive index data for the respective cell types are tabulated in The method of detecting cancer with the proposed BKFurthermore, for skin , cervical (HeLa), adrenal gland (PC12), blood (Jurkat), and breast (MCF-7 and MDA-MB-231) normal and cancerous cells, the resonance and SPR angle shifts are 4.2 deg, 5.9 deg, 3.7 deg, 4 deg, 4.1 deg, and 3.9 deg, respectively. Therefore, the resonance angle angular shift sensitivity of the skin , cervical (HeLa), adrenal gland (PC12), blood (Jurkat), and breast (MCF-7 and MDA-MB-231) normal and cancerous cells are 210 deg/RIU, 245.83 deg/RIU, 264.285 deg/RIU, 285.71 deg/RIU, 292.86 deg/RIU, and 278.57 deg/RIU, respectively, as calculated using Equation (12). 7/TiO2/Au (50 nm)/graphene sensor was designed focusing on the various types of cancer detection, it is also capable of detecting a wide range of biological solutions. Most biological solutions have a refractive index in the range of 1.33 to 1.41. Therefore, the numerical results regarding changes in the sensing medium’s refractive index are plotted in Although the proposed (BK7/TiO2/Au (50 nm)/graphene sensor is y = 197.5 × x − 192.4, and the regression coefficient is R2 = 0.9858, as shown in In order to measure a high refractive index, sensor linearity is a precondition ,83. The Finally, the comparison between our proposed biosensor and some recently reported works demonstrates that our proposed biosensor is highly sensitive in terms of angular sensitivity, DA, FOM, and SNR, as tabulated in In this article, a surface plasmon resonance-based biosensor has been proposed on the basis of the angular-based detection method for detecting cancer biomarkers. However, there are various methods of detecting biomarkers using the SPR-based method, including the wavelength-based detection method and the reflection intensity-based detection method. Each of these methods detects biomarkers with different approaches, and each has a specific focus on the detection sensitivity. For instance, the spectral mode analysis method can be used to improve the spectral sensitivity and FOM, as demonstrated in , but it 2 /Au/graphene layers, conduct an analysis of the thickness of the Au layer, and conduct an analysis of the graphene layers to find the best sensitivity of the sensor. The numerical results exhibit angular sensitivities of 210 deg/RIU, 245.83 deg/RIU, 264.285 deg/RIU, 285.71 deg/RIU, 292.86 deg/RIU, and 278.57 deg/RIU, respectively, for skin , cervical (HeLa), adrenal gland (PC12), blood (Jurkat), and breast  cancer types. Additionally, the obtained detection accuracy (DA), figure of merits (FOM), and signal-to-noise ratio (SNR) demonstrate values of 0.263 deg−1, 48.02 RIU−1, and 3.84, respectively. Moreover, the 2D graphene layer improves the diversity of biosensing applications as well as enhances the biological detection capability of the biosensor by absorption of a biomolecule and bonding with the carbon-based rings that widely exist in biomolecules. For this, we have also analyzed our sensor for the detection of a wide range of biological solutions, obtaining a high sensor linear regression coefficient (R2) of 0.9858. As the proposed biosensor could be accomplished utilizing the subsisting fabrication technologies and as enormous advances in nanotechnology have demonstrated significant breakthroughs in plasmonic sensing, this might bring many extensively promising opportunities in future medical applications for cancer detection and other biosensing applications.The rapid advancements in biomedical research over the past few years have shown a significant demand for biosensing with high sensitivity, specificity, and throughput. Biosensors with extremely high sensitivity and excellent identification specificity are anticipated to detect certain biomolecules. Surface plasmon sensors are among the best current sensing technologies because of their beneficial qualities, including their high sensitivity, short response times, and ability to conduct real-time label-free sensing when biomolecules interact with the sensor surface. This article proposes a multilayer coated SPR sensor based on graphene for early-stage cancer detection using numerical approaches. Due to the fact that the design and characteristics of multilayer arrangements substantially influence the optical responses of plasmonic sensors, we therefore have performed a detailed numerical analysis of the materials used. We assess the impact of the TiO