Graphene based room temperature flexible nanocomposites were prepared using epoxy thermosets for the first time. Flexible behavior was induced into the epoxy thermosets by introducing charge transfer complexes between functional groups within cross linked epoxy and room temperature ionic liquid ions. The graphene nanoplatelets were found to be highly dispersed in the epoxy matrix due to ionic liquid cation–π interactions. It was observed that incorporation of small amounts of graphene into the epoxy matrix significantly enhanced the mechanical properties of the epoxy. In particular, a 0.6 wt% addition increased the tensile strength and Young’s modulus by 125% and 21% respectively. The electrical resistance of nanocomposites was found to be increased with graphene loading indicating the level of self-organization between the ILs and the graphene sheets in the matrix of the composite. The graphene nanocomposites were flexible and behave like ductile thermoplastics at room temperature. This study demonstrates the use of ionic liquid as a compatible agent to induce flexibility in inherently brittle thermoset materials and improve the dispersion of graphene to create high performance nanocomposite materials. However, a major challenge in the fabrication of such flexible devices is the unavailability of suitable materials that combine high conductivity, mechanical flexibility and stability in electrochemical environments. Furthermore, most of the commonly used polymer matrices rapidly degrade at relatively low temperature3. The use of permanently cross-linked polymer structures such as epoxy thermosets could potentially offer high mechanical properties and stability4. They have high dimensional stability, high mechanical, thermal, and environmental resistance; and are therefore utilized in many challenging applications5.There has recently been great interest in making flexible/bendable electronics such as rollup displays and wearable devices with graphene based polymer composites typically being used as a flexible substrate7 based on addition-fragmentation chain transfer reactions in the presence of radicals9. However, such networks show limited reversibility and the chemical equilibrium can be displaced towards depolymerisation, leading to unfavorable network structure and performance10. Leibler et al. reported the synthesis of reversible epoxy networks based on exchange reactions that lead to thermoset materials with high levels of stress relaxation and recyclability11. This approach was further extended to other olefin containing polymers12.Thermoset epoxies are however highly brittle materials and thus offer no or limited flexibility. There are a few reports that focused on the formation of cross-linked networks that can disrupt and reform13. Here, ILs act as miscible molecular liquids to form charge transfer complexes with the epoxy and thus become part of the cross-linked network giving the materials distinctive thermo-mechanical properties14. Moreover, ILs are also known to possess excellent graphene dispersion capabilities15. Imidazolium based ILs have been used to make stable dispersions of reduced graphene oxide at relatively high concentration without using any surfactants/stabilizers. In this work, epoxy based flexible graphene nanocomposites were successfully prepared and characterized for their use in functional applications.Here we report an epoxy/graphene nanocomposite that is flexible and deformable after cross-linking and behaves like ductile thermoplastics. The flexibility was induced by the introduction of an imidazolium based room temperature ionic liquid. Structurally, ILs are molecular ions containing a bulky organic cation and a small anion® graphene nanoplatelets. The platelets have an average dimeter of 5 micron and a typical surface area of 120–150 m2.g−1. The epoxy precursor diglycidyl ether of bisphenol A (DGEBA) with an epoxide equivalent weight of 172–176 g.mol−1 and the curing agent 4,4′- methylenedianiline (MDA) were purchased from Aldrich Chemical Co. The ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) was obtained from Fluka. The chemicals were used as received.Graphene nanoplatelets were obtained from XG Sciences commonly known as xGnP16 where it was observed that materials with high level of room temperature flexibility were only achieved at 40% of [BMIM][Cl] in epoxy. An IL content below 40% was found to be more ductile and rigid and at more than 40% of IL content the material started to loose stability and integrity. Epoxy mixtures containing 40 wt% IL were mechanically stirred for 1 hour. For the fabrication of epoxy composites pre-weighed amounts of nanoplatelets were first suspended in the epoxy [BMIM][Cl] mixture and then sonicated  for 1 hour. The resulting suspensions were mechanically stirred for 2 hours and then mixed with MDA. After complete dissolution of the MDA, the whole mixture was poured into pre-heated (100 °C) moulds, cured at 150 °C for 10 hours and then post-cured at 180 °C for 2 hours, with excess ILs were extracted out. Imidazolium based room temperature ILs possess high thermal stability. The decomposition temperature of BMIMCl is 291 °C. Hence the high temperature curing and post curing has no impact on the stability of IL or the nanocomposites.Epoxy resin containing all concentration of IL was studied in our previous research1. The q range was from 0.008 to 0.5 Å−1. An in-vacuum undulator source  at a beam energy of 9 keV was used. The exposure time for each sample was 2 s and tests were performed at 25 °C. The intensity profiles were interpreted from the plot of scattering intensity (I) as a function of scattering vector (q) which is related to the scattering angle θ by the relationship q = (4π/λ) sin (θ/2).The small angle x ray scattering (SAXS) beam-line at the Australian Synchrotron was used with a 1.6 m camera length to investigate the scattering patterns following a previously described procedureTg was taken as the maximum of the tan δ curve in the glass transition region.Dynamic mechanical tests were performed on a TA Q800 dynamic mechanical thermal analyzer (DMTA) operating in dual cantilever mode with a frequency of 1 Hz and a heating rate of 3 °C/min. The specimen dimensions were 60 mm × 12 mm × 3 mm. The storage modulus, loss modulus and tan δ were measured from 30 to 250 °C. The The tensile properties of the composites were measured on an Instron 30 kN SD tensile testing machine. The tests were conducted using dumb-bell shaped specimens according to ASTM standard D638. A minimum of five specimens were tested for each sample and the average values reported.Tg values were taken as the midpoint of the transition in the second scan of the DSC thermograms.DSC experiments were performed under a nitrogen gas atmosphere on a TA-DSC model Q200 instrument using 5–10 mg of each sample. The samples were first heated to and held at 100 °C for 5 min to remove the thermal history. The samples were cooled to −80 °C at a rate of 20 °C/min, held for 5 min, and finally heated from −80 to 250 °C at a rate of 20 °C/min (second scan). The The electrical resistivity of the samples was determined using an electrical resistivity cell with variable resistor and a distance between the electrode probes set at 1 cm. Prior to testing, the samples were polished for 30 seconds using 1200 grit paper at 150 RPM on a Struers Rotopol-1 polish machine .The morphologies of the nanocomposites were examined using a Zeiss Supra 55VP scanning electron microscope (SEM) operating at an accelerating voltage of 5 kV and a working distance of 10 mm. The cryo-fractured surfaces were coated with thin layers of gold to avoid charging.−1 using a Bruker RFS-100 FT-Raman spectrometer equipped with an Adlas Nd:YAG laser and a liquid nitrogen cooled Germanium diode detector. The samples were held on a mirrored backing in 180° backscatter geometry. Data acquisition, 256 scans, was performed using Bruker OPUS software (version 3.1). The laser power was 500 mW. A Blackman-Harris 3-term apodization function was used. Data manipulation was carried out using Grams AI software v9.1.Raman spectra were obtained at 1064 nm excitation and a resolution of 4 cm−1 and averaged over at least 4 scans, each with an accumulation time of 40 s. The Raman shifts were calibrated using the 520 cm−1 line of a silicon wafer. The spectral resolution was~1 cm−1. Data collection and manipulation was carried out using WiRE 4.2 software.Raman spectra were obtained at 514 and 785 nm excitation using an inVia confocal microscope system  through a x50 (0.75 na) objective. Incident laser powers were 0.8 mW (514 nm) and 2.3 mW (785 nm) and a coaxial backscatter geometry was employed. Spectra were collected over the range 100 to 3200 cm16. It has been reported that by varying the epoxy - ionic liquid ratio, materials could be produced that can exhibit distinct physical and mechanical characteristics ranging from those of brittle thermosets, to perfectly ductile thermoplastics, to elastomers. In the present work, a plastic-like thermoset composition was chosen to form the matrix for graphene nanocomposites. This matrix composition was prepared by using epoxy and the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) at a 60/40 (w/w) ratio. At room temperature, this cured thermoset composition can be bent and twisted by applying a relatively small force and the polymer retains the new shape even after the force is removed. The room temperature flexibility of these thermoset materials were explained by the confinement of ionic liquid molecules within the highly cross-linked thermoset and the charge triansfer complex formation between the components. Here, with a high ionic liquid content (40%), the bulky ions form a coupling between the epoxy cross links which break and reform when external forces are applied resulting in the flexibility of the material at room temperature.Thermal flexibility behavior can be induced in epoxy thermosets by introducing ionic liquid charge transfer complexes between functional groups within cross linked epoxy and ionic liquid ions17 and polymer nanocomposites18. The dispersion of individual CNTs and the curing of epoxy, both controlled by ionic liquids, were achieved in our laboratory19. In the present work, the combination of graphene platelets with ionic liquids leads to a high level of dispersion which was then utilized in making a particular type of room temperature flexible nanocomposites with improved properties. The graphene nanoplatelets were used “as received” without any purification or functionalization knowing that ionic liquids can uniformly disperse graphene. The high level of dispersion of the graphene nanoplatelets with the aid of the IL is clear from Fig. The non-covalent dispersion of carbon nanomaterials such as carbon nanotubes and graphene has been critical in the preparation of nanocomposites to increase the utilization of these materials while maintaining their inherent reinforcing and electronic properties. Ionic liquids have been investigated extensively in the past and found to be excellent non-covalent dispersing agents for carbon nanotubes (CNTs) in preparing bucky gels−1 (200 eV). This weak feature would be easily masked by the strong aromatic ring modes of the epoxy. While graphene is inactive and multiple layer of graphene absorb weakly in the infrared, both can be easily detected using Raman spectroscopy. Raman mapping with its high spatial resolution of 0.5 μm between analysis spots has potential to reveal the spatial distribution of the graphene within the epoxy matrix. While excellent Raman spectra were collected from the epoxy and epoxy/IL mixtures using both 785 and 1064 nm excitation, once the graphene was added no useful data could be obtained (not shown). Raman spectra of graphene are easily obtained using visible excitation. The epoxy was found to fluoresce, washing out all Raman spectral features, when 514 nm excitation was utilized (not shown).When a few layers of graphene are present, splitting of the G mode phonon makes it become active in the infrared spectrum near 1613 cm20.The distribution of graphene nanoplatelets in the epoxy/[BMIM][Cl] matrix was first examined using SEM. The SEM images of a graphene epoxy nanocomposite with a 0.6 wt% graphene loading shown in Fig. πα = 2.293%, where α = e2ћc 22. This means that over this spectral region each graphene layer absorbs 2.3% of the incident light. The optical absorption in graphene is dominated by interband transitions from the mid-infrared to the ultraviolet22. In this study, the absorption in the near infrared region (>0.8 eV) has been used to precisely determine the number of graphene layers present in sample comprised of 3 to 6 layers23.The composites were further analyses using Raman spectra (not shown). In the infrared-to-visible spectral range, the expected absorbance has been calculated to be independent of frequency and to have a magnitude given by 24. SAXS investigations of the nanocomposites were therefore performed to probe the degree of dispersion of the graphene within the reinforcing matrix. Interestingly, little difference in scattering signals can be observed, even at high graphene loading, over the q range investigated. The Lorentz plots (I(q)q2 vs q) shown in Fig. 25, and that the ILs provided a suitable platform to improve graphene dispersability26.Representative SAXS profiles in terms of intensity as a function of scattering vector q for different graphene loadings are presented in Fig. 27. It is apparent that graphene nanoplatelets can significantly enhance the mechanical properties of epoxy/ionic liquid flexible thermosets. This mechanical enhancement can be attributed to (i) high inherent elastic modulus and strength of graphene nanoplatelets (ii) better interactions between graphene and the epoxy/[BMIM][Cl] matrix and (iii) a more uniform graphene dispersion in the epoxy due to the presence of ionic liquid.Figure Tg of around 44 °C. The Tg of the flexible epoxy matrix remains about the same with the addition of graphene nanoplatelets and only decreases marginally (~3 °C) at higher (0.8 and above) graphene loading. In the previous research it was found that epoxy containing 40% IL become very soft when heated above Tg. Generally a reduction in Tg is attributed to either molecular chain confinement by the graphene sheets or the impact of the graphene sheets on the cross linking reactions of the epoxy4. In both cases, the polymer cross-link density decreases leading to an increase in polymer chain mobility.The thermal and thermo-mechanical properties of the nanocomposites were analyzed and the results are shown in Figs Tg of the epoxy remain more or less unchanged with the addition of graphene.The storage modulus of epoxy was found to improve with the addition of graphene Fig. . At room28. Such interactions would likely lead to a level of polarization of the structure, which was also experienced when testing the samples, as all the IL graphene composite materials exhibited a capacitor behavior by altering the charge propagation and overall surface charge of the bulk material at the graphene-epoxy interfaces29. The stabilization of the current across the samples was slow, and took up to a few minutes for the highest graphene loadings. The use of polymerizable ionic liquid crystals may offer opportunities to further reinforce such matrixes and generate epoxy resin materials into semi-conducting structures with various levels of electronic responses30.Interestingly, the electrical conductivity of the graphene IL composites was found to decrease with graphene loading content Fig. . The barThe graphene nanocomposites were all flexible at room temperature. The materials can be reversibly bent or twisted many times by applying a local force. Figure While commonly reported for thermoplastics, inducing flexibility into thermosets and fabricating bendable and foldable nanocomposite materials remains a great challenge. This is primarily due to the lack of suitable materials that combine both mechanical flexibility and superior conductivity for their high performance in electronic devices. Room temperature flexible nanocomposites were here prepared for the first time using epoxy and graphene nanoplatelets. An IL was used to induce network flexibility into a cross-linked epoxy thermoset resin. The IL also served as a functional dispersant for graphene nanoplatelets. A morphological investigation showed highly dispersed nanoplatelets in the matrix phase with the high level of dispersion attributable to the interaction between graphene and ionic liquid. The incorporation of graphene significantly improved the tensile mechanical properties of the epoxy with a huge 125% improvement in tensile strength. The storage modulus showed a 50% improvement at a 0.6 wt% graphene loading whereas the thermal properties of epoxy were not affected by the incorporation of the graphene. The nanocomposites and films show high levels of flexibility at room temperature where it almost behaved like a thermoplastic. It has been identified that the strong interaction between bulky IL ions and the epoxy hydroxyl groups link the brittle epoxy chains network. During physical deformation (or when heated), such secondary bonds reversibly break leading to flexible cross-linked networks. The electrochemical properties have to be further investigated to explore the potential of these materials in flexible electronic devices.


Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF’s positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO’s excellent sensing properties and SF’s flexibility, expediting the production of flexible, low power consumption devices at relatively low costs. The onset of the internet of things (IoT) and virtual reality (VR) demands the development of flexible, portable devices ,2. TheseIn fact, several approaches have been investigated for this purpose via implementing adhesive intermediates between GO and selected objects for better adhesion ,31,32 MeGO, dispersed with a concentration of 0.1 wt % (1 mg/mL) in DI water, is negatively charged due to the oxygen functional group attached to the GO. In contrast, an SF surface tends to be positively charged due to static electricity. The static electricity occurs due to an electrical charge imbalance on the SF surface, which has a high electrical resistance to the charged carrier. The magnitude of the static electric force on the SF surface varies depending on the tendency of the electrons to move from the SF to another material when the SF contacts and separates from that material . −1 from the SL, the presence of GO was set at 1, and the absence of GO was set at 0. The Raman mapping results show that high quality GO was uniformly and seamlessly coated on the SL rubbed against the latex glove, while the GO was lightly coated on the SG rubbed against the glass bar. This clearly indicates that the surface of the SF rubbed against the latex became more positively charged than that rubbed against any other materials in this work. By extension, this SF surface attracted more GO. In addition, the Raman analysis clearly distinguished the SA and SL, as shown in The uniformity and quality of the GO coating on the SF were further investigated via a Raman analysis. No peaks were observed from the SW, but the peaks representing the GO began to be observed and were fully observed from the SA and SL, respectively, as shown in The electrical properties of the GO-coated SF (SL) was further investigated at various coating times, as shown in 2O. The humidity in the air was quantified via the capacitance as shown in Finally, the SLs were implemented as an active sensing material between two Cu plates for capacitive humidity sensor applications, as shown in In summary, flexible silk fiber (SF) was coated with graphene oxide (GO) via electrostatic force without adhesive intermediates. It was found that the electrostatic force, i.e., the adhesion force, between the GO and SF could be controlled. The GO was uniformly and seamlessly coated on the SF in a large area, which was characterized by optical image, secondary electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and a Raman analysis. In addition, the electrical properties of the GO-coated SF were investigated as a function of coating time and temperature. The GO-coated SF showed the feasibility of capacitive humidity sensor, unlike the intact SF. This approach allows the humidity sensor to take advantage of GO’s excellent sensing properties and flexibility. Therefore, it is expected that this method will enable the production of flexible, low power consumption devices at relatively low costs.


IG and ID) were used to identify the graphene domain boundaries. The domain boundaries were also identified using Raman images of ID/IG and I2D/IG ratios and 2D spectral widths. Interestingly, the ID maps showed that the defects within individual domains significantly increased for the graphene with large domain size. The correlation analysis between the G and 2D peak energies showed that biaxial tensile strain was more developed in the graphene with large domain size than in the graphene with small domain size. Furthermore, spatial variations in the spectral widths of the 2D peaks over the graphene layer showed that strain fluctuations were more pronounced in the graphene with large domain size. It was observed that the mobility (sheet resistance) was decreased (increased) for the graphene with large domain size. The degradation of the electrical transport properties of the graphene with large domain size is mainly due to the defects, tensile strains, and local strain fluctuations within the individual domains.We report spatially resolved Raman scattering results of polycrystalline monolayer graphene films to study the effects of defects, strains, and strain fluctuations on the electrical performance of graphene. Two-dimensional Raman images of the integrated intensities of the G and D peaks ( In the CVD-grown large-area graphene, however, the formation of graphene domain boundaries, structural defects, and built-in strains cannot be avoided. Consequently, the electrical, mechanical, and thermal properties of polycrystalline graphene are inevitably altered by the presence of the domain boundaries, defects, and strains5. Defects at the domain boundaries can act as scattering sites of charge carriers, leading to inferior electrical transport properties. For example, the carrier mobility of polycrystalline graphene tends to decrease for a small domain size, suggesting that the charge transport is influenced by scattering at the domain boundaries7. In contrast, the presence of defects within the graphene domain can lead to a reduction in mobility even for a large domain size11. The tensile strain in the graphene layer induces a decrease in the carrier mobility and an increase in the sheet resistance of the graphene14. Furthermore, random strain fluctuations and wrinkles also limit the carrier mobility16. Therefore, the physical properties of polycrystalline graphene are influenced by not only the defects at the domain boundaries but also other defects, strains, and strain fluctuations within the individual domains.Large-scale growth of high-quality crystalline graphene is a prerequisite for improving the device performance in graphene-based nanoscale applications. Chemical vapor deposition (CVD) is one of the widely used methods to grow graphene over a large area17. The 2D peak originates from a double-resonance electron-phonon scattering process involved with the electronic dispersion of graphene17. Therefore, the 2D peak facilitates the determination of the graphene thickness because the electronic band structure of graphene varies as a function of the number of layers17. The symmetric 2D peak of single-layer graphene becomes dispersive with an increase of the number of layers owing to the interlayer coupling, leading to the broadening of spectral width18. The G peak has E2g symmetry involving the C–C bond stretching and originates from a first-order Raman scattering process17. Both the G and 2D peaks are sensitive to strain20. Further, a correlation study of the G and 2D peak energies can explore the residual strain, which would affect the electrical transport properties of graphene21. Therefore, two-dimensional Raman images of the energies, intensities, and/or widths of the D, 2D, and G peaks scanned over a large area of graphene can provide useful information on the spatial distributions of defects, strains, strain fluctuations, etc. In this study, Raman mapping measurements were carried out on single-layer graphene samples to investigate the influence of defects, strains, and strain fluctuations on the transport properties in the presence of domain boundaries. We observed previously that the sheet resistance (mobility) increased (decreased) for the graphene with a large domain size11. Raman images revealed direct evidence that the spatial distributions of defects and strains were different for graphene samples with different domain sizes. Consequently, we observed that the electrical transport properties of the graphene devices could be affected by not only the carrier scattering at the domain boundaries but also the defects, strains, and strain fluctuations within the individual domains.Raman scattering is a powerful tool to probe defects in graphene because the D peak is activated in the presence of disorder11. Thermal annealing leads to the oxidation of the Cu foil. Since the Cu foil underneath the domain boundaries is more vulnerable to the penetration of O2 molecules through defects in graphene, the domain boundaries are distinctly visible as the bright lines in the SEM images22. The electrochemical polishing (ECP) treatment combined with an annealing process suppresses the formation of graphene nucleation sites, resulting in an increase in the domain size23. Indeed, the average domain size of sample B (∼293 μm2) grown using the ECP-treatment followed by the atmospheric pressure H2 annealing process is significantly larger than that of the untreated sample A (∼66 μm2). Generally, the sheet resistance of polycrystalline graphene is expected to decrease as the graphene domain size increases24. In the current study, the sheet resistance was observed to increase for the larger domain size: ∼552 Ω sq−1 for sample A and ∼777 Ω sq−1 for sample B11. Moreover, the mobilities were measured to be approximately 1530 and 910 cm2/V·s for samples A and B, respectively11. The decrease of the mobility of sample B may be caused by the copper oxide on the surface which was not fully removed due to the suppressed sublimation of copper and oxygen in the atmospheric pressure of H2. The copper oxide may induce defects and strain by forming carbon-oxygen bonds and/or small pores on graphene11.Figure −1. The 2D peak energy for sample A is observed at 2700 cm−1, that is consistent with the 2D energy value for an excitation laser energy of 2.54 eV (488 nm)25. The 2D peak has a narrow, single Lorentzian line shape and is much more intense than the G peak: a typical signature of monolayer graphene17. The weak Raman mode at ∼2450 cm−1 corresponds to a multi-phonon response that originates from the combination of the D peak and the longitudinal acoustic phonon17. Interestingly, both the G and 2D peaks of sample B are shifted downward in energies compared to the corresponding peak energies of sample A. Moreover, the spectral width of the 2D peak of sample B is much broader than that of sample A. The changes in the G and 2D peak energies and spectral widths in monolayer graphene usually originate from strain and/or strain fluctuations. In order to clarify the differences observed between the samples in more detail, it is necessary to perform spatially resolved Raman measurements over a large area.Figure 26. Polycrystalline graphene consists of single-crystal domains with different crystallographic orientations. The individual domains are merged together with the formation of defects, wrinkles, and/or overlapped structures at the domain boundaries27. Moreover, defective or atomically smooth connections can be formed at the domain boundaries with flat interfaces27.Raman intensity changes in CVD-grown monolayer graphene are mainly related to defects, (folded) wrinkles, and overlaps of the graphene layers. Wrinkles are usually formed during the post-growth cooling of graphene on a Cu substrate owing to the difference in thermal expansion coefficients between graphene and Cu27. The integrated intensities of the G and 2D peaks may not vary regardless of the nature of the interface: either a perfect or a defective flat interface28. In contrast, for the multilayer graphene boundary and the folded wrinkle, the integrated intensity of the G peak (IG) usually increases owing to an increase in the number of graphene layers compared to the surrounding monolayer region30. The integrated intensity of the 2D peak (I2D) decreases at the wrinkle (not folded) owing to a structural curvature effect, whereas the integrated intensities of the G and D peaks do not change at the wrinkle26. At the overlapped bilayer domain boundary, I2D depends on the twisted stacking angle between the misoriented monolayer graphene domains31. Therefore, spatial mappings of the integrated intensity changes in the graphene Raman modes can provide direct spectral evidence on the defects and domain boundary characteristics in polycrystalline monolayer graphene.The D peak is activated for a defective interface but not for an atomically smooth, perfect interface at the domain boundaryIG and ID for samples A and B. Note that the samples were not mild dry annealed. Interestingly, the IG image shows individual domains separated by boundaries with a relatively large IG (marked by dashed curves). Furthermore, the ID image also exhibits the same boundary structures. The representative Raman spectra in Fig. IG and ID are usually developed at a folded wrinkle or a bilayer domain boundary26. Therefore, the domain features observed in both IG and ID images suggest that the enhancements in the G and D peak intensities are mainly attributed to the formation of the graphene domain boundaries. The shape and size of the domains in the Raman mapping images are very similar to those shown in the SEM images  is usually related to an increase of defect density, which occurs more at the domain boundaries. It has been reported that the ID/IG ratio does not show a discernable enhancement at the folded wrinkle10. Therefore, it is likely that the domain boundary consists of the overlapped graphene. Although sample B shows similar features as sample A in the ID, IG and ID/IG images, two noticeable differences are clearly observed. The average domain size increases significantly from ∼52 μm2 (sample A) to ∼254 μm2 (sample B) and the D peaks are developed not only at the domain boundaries but also within the domains. The macro-Raman spectra in Fig. −1) is higher than that of sample A (∼552 Ω sq−1). Therefore, one of the main causes of the increase in the sheet resistance of sample B is attributed to the significant increase of defect density within the domains  and spectral width (Γ2D) are mainly sensitive to strain and strain fluctuations, whereas ωG and ΓG are sensitive to not only strain but also doping21. Figure ω2D and Γ2D for sample A over the same area shown in Fig. 2D image of sample A clearly illustrates that the spectral widths are broadened at the domain boundaries, whereas the ω2D image does not resolve the domain boundary structure. In comparison, the domain structures are not resolved in both the ωG and ΓG images  in the sheet resistance (mobility) of graphene14. Therefore, the increase (decrease) in the sheet resistance (mobility) of sample B is partly attributed to the tensile strain in sample B as compared to sample A.In comparison to sample A, the 2D peak energies are significantly shifted downward over the entire area in sample B, indicating the presence of tensile strain. The spatially averaged values of the 2D peak energies for samples A and B are ω2D and ωG maps provide the variations in the 2D and G peak energies over the scanned areas. Histograms extracted from the distributions of ω2D and ωG over the scanned areas show that the energy variations are more dispersive in sample B than in sample A  than in sample A (−1). The increase in the spatially averaged value of Γ2D of sample B compared to that of sample A is a signature of a larger magnitude of random strain fluctuations15. Therefore, the statistical broadenings of both the 2D peak energy and width distributions as well as the larger average value of the 2D spectral width in sample B suggest that strain fluctuations are more pronounced in sample B than in sample A. These observations provide evidence that the random strain fluctuations are one of the dominant sources of disorder that limits the carrier mobility observed in the electrical transport measurements .Spatially resolved e A Fig. . This is ΓG Fig. . EspeciaωG and ω2D provides useful information on strain and can differentiate the effect of strain from that of doping on graphene35. For example, for monolayer graphene under biaxial tension, the strain-induced shift of the 2D peak energy is approximately twice that of the G peak energy36. Local strain fluctuations in monolayer graphene can cause spatial variations in the G and 2D peak energies over the graphene layer. Consequently, the correlation points  of the G and 2D peak energies scatter along a line with a slope of 21. Similarly, in our case, the correlation points  extracted from the Raman images in Fig. 21. The scattered points  in sample B are located in the lower part of the correlation plot, clearly indicating that sample B is relatively under tensile strain as compared to sample A.The correlation analysis of ID and IG but also ID/IG and I2D/IG ratios reveal domain boundary characteristics. Interestingly, the Γ2D image also reveals the domain boundary structures. As indicated by the increase of ID within the domains, the decrease in Two-dimensional Raman imaging measurements show that the spatial mappings of the spectral variations in the graphene Raman modes provide a unique opportunity to simultaneously probe domain boundary structures, defect distributions, strains, and strain fluctuations, all of which limit the transport properties of polycrystalline graphene. Raman images of not only 2) flow condition for 45 min. The graphene films were synthesized on the Cu foils using methane (CH4) and H2 gas mixture for 12 min. The sample A (B) was grown on a Cu foil annealed at low (atmospheric) pressure condition of H2 without (with) the ECP treatment. After the synthesis of the graphene films, the CVD chamber was rapidly cooled to room temperature.Single layer graphene films were synthesized on copper (Cu) foils using CVD method. Two different types of Cu foils were used: one was annealed at low pressure without ECP treatment and the other was annealed at atmospheric pressure after ECP treatment. ECP treatment was performed in a mixed solution of phosphoric acid and deionized water. Pre-treated Cu foils were cleansed with deionized water, acetone, and isopropanol in a regular sequence. The Cu foils were heat treated at 1050 °C under hydrogen  at room temperature. The power of the excitation laser was less than 0.5 mW, at which any laser-induced thermal effects on the samples were not observed. Scattered light from the graphene surface was collected through the same objective lens, dispersed through a spectrometer with a grating of 1200 grooves/mm, and detected using a thermoelectrically cooled charge-coupled device detector. The incident laser polarization was parallel to the scattered light polarization throughout the Raman mapping measurements. The spectral resolution was ∼1 cm−1. The spectrometer was calibrated using the known spectral lines of a mercury gas light source.Spatially resolved Raman scattering measurements were performed on the graphene films transferred onto SiO


Antibody blockade of the PD-1/PD-L1 pathway has elicited durable antitumor responses in the therapy of a broad spectrum of cancers. PD-L1 is constitutively expressed in certain tumors and host immune cells, and its expression can be induced or maintained by many factors. The expression of PD-L1 on tumor tissues has been reported to be positively correlated with the efficacy of anti-PD-1/PD-L1 therapy in patients. However, multiple clinical trials indicate that patients with PD-L1-negative tumors also respond to this blockade therapy, which suggests the potential contribution of PD-L1 from host immune cells. Recently, six articles independently evaluated and verified the contributions of PD-L1 from tumor versus non-tumor cells in various mouse tumor models. These studies confirmed that PD-L1 on either tumor cells or host immune cells contributes to tumor escape, and the relative contributions of PD-L1 on these cells seem to be context-dependent. While both tumor- and host-derived PD-L1 can play critical roles in immune suppression, differences in tumor immunogenicity appear to underlie their relative importance. Notably, these reports highlight the essential roles of PD-L1 from host myeloid cells in negatively regulating T cell activation and limiting T cell trafficking. Therefore, comprehensive evaluating the global PD-L1 expression, rather than monitoring PD-L1 expression on tumor cells alone, should be a more accurate way for predicting responses in PD-1/PD-L1 blockade therapy in cancer patients. Antibody blockade of the programmed death-1 receptor/programmed death-ligand 1(PD-1/PD-L1) signaling pathway has shown unprecedented durable therapeutic responses in patients with a variety of cancers. Accumulating studies in animal models and clinical trials have contributed to our current understanding of mechanisms underlying the efficacy of PD-1/PD-L1 pathway blockade in cancer immunotherapy. Since PD-L1 on tumor cells plays an important role in preventing T cell-mediated killing, beneficial outcome of PD-1/PD-L1 blockade therapy has been correlated with PD-L1 expression on tumor cells , suggestElucidation on the contributions of tumor cells and host immune cells-derived PD-L1 has important clinical implications as PD-L1 expression may predict the sensitivity of anti-PD-1/PD-L1 immunotherapy in cancer patients. Within 1 year from early of 2017, six independent research groups published papers in high impact journals and explained their points of view on the contributions of PD-L1 expressed from relevant cells –8. Mouse−/− mice to test whether PD-L1 expression on tumor cells was required for tumor immune escape. While growing T3ΔPDL1 tumors were observed in all of the Rag2−/− mice, the majority of inoculated T3ΔPDL1 clones were spontaneously rejected in syngeneic WT mice. Furthermore, T3ΔPDL1 cells with enforced expression of PD-L1 regained the capacity to form progressively growing tumors in WT mice. These facts revealed that PD-L1 expression on T3 sarcoma cells was functional in suppressing antitumor immunity in the model. In addition, Noguchi et al. [Noguchi et al.  generateLau et al.  used gen+ T cells for the antitumor effects of PD-L1 antibody therapy.Kleinovink et al.  have als−/− PD-L2−/− mice, PD-L1 expression on the tumor cells is the only source of ligands for PD-1.They found that MC38 tumor growth was similarly robust in PD-L1−/− PD-L2−/− and WT mice, which indicates that engagement of PD-1 by PD-L1 on tumor cells alone is sufficient to suppress antitumor immunity to MC38 tumors. Consistently, administration of PD-L1-blocking antibody to MC38 tumor-bearing PD-L1−/− mice resulted in tumor clearance in the majority of mice. Juneja et al. [−/− mice compared with WT mice. This suggests that PD-L1 expression on non-tumor cells in WT mice plays a nonnegligible role in inhibiting antitumor immunity to melanoma tumors.Juneja et al.  first tea et al.  also use−/− mixed bone marrow chimera mice model, they elegantly demonstrated that blocking PD-L1 on CD11b+ myeloid cells is indispensable for effective antitumor immunity in PD-L1 blockade therapy.Tang et al.  used MC3−/−, NSG, PD-L1−/− and PD-1−/− mice, for studying PD-L1 and PD-1 signaling blockade in MC38, ID8 (ovarian cancer), B16-F10 (melanoma), and LLC (lung cancer) tumor models. First, they verified that host immunity determines anti-PD-L1-induced tumor immunity. While WT mice bearing various tumors had effective response to PD-L1 blockade, anti-PD-L1 treatment had no antitumor effect in NSG and Rag1−/− mice. Their further experiments indicate that anti-PD-L1 treatment reduced tumor growth in mice bearing PD-L1-deficient MC38, ID8 and B16-F10 tumors, which implies that host- but not tumor-derived PD-L1, is indispensable for the therapeutic efficacy of anti-PD-L1 treatment. Mechanistically, the authors experimentally proved that anti-PD-L1 treatment activates T cells in tumor and draining lymph nodes. They demonstrated that tumor-associated APCs (antigen-presenting cells), as the major PD-L1+ immune cells, are the major immune targets of anti-PD-L1 therapy. Additionally, they observed a well correlation between expression of PD-L1 on dendritic cells (DCs)/macrophages and the efficacy of treatments with either anti–PD-1 alone or in combination with anti-CTLA-4 in ovarian cancer and melanoma patients. They concluded that the host immune system is indispensable for PD-1/PD-L1 blockade therapy, and the host DCs and macrophages-derived PD-L1, rather than cancer cell-intrinsic PD-L1, predominantly accounts for the blockade therapeutical efficacy.Lin et al.  used mic−/− and PD-L1+/+ tumors in WT host, Lin et al. demonstrated the critical role of host-derived PD-L1 by treating the host with anti-PD-L1 antibody, which resulted in significant tumor regression [+ T cell cytotoxicity and suppressing antitumor immunity in their model [From multiple angels and using various techniques and pre-clinical tumor models, these studies reveal that PD-L1 on tumor cells and host cells is involved in tumor immune evasion. All the studies employed gene silencing technologies to knock out of PD-L1 in tumors, and these tumors were inoculated to WT immune competent hosts to test the roles of PD-L1 in tumor immune escape Fig. a. While gression . Both Tair model , Tang etir model , 8. The ir model . This su−/−PD-L2−/− and WT mice [−/− mice compared with WT mice [Most of these studies implanted PD-L1-sufficient tumors to PD-L1 knock out hosts to test the contribution of PD-L1 in suppressing the antitumor T cell responses Fig. b. While  WT mice . This di WT mice . In addi WT mice , 8. Howe WT mice , 8.Besides, functional consequences of different levels of PD-L1 expression on tumors were assessed from Noguchi et al. by comparing physiological level and over-expressed level of PD-L1. They found that abnormally high expression of PD-L1, but not levels of PD-L1 expression that can be induced on tumor cells under physiologic conditions, is required to prevent immune elimination of highly immunogenic unedited MCA sarcoma cells that express strong neoantigens . Their w+ T cells dependent cell-extrinsic pathways [−/− tumors, including reduced MHC-I expression and increased PD-L2 expression [+ cytotoxic T lymphocytes (CTLs), and is dominant in suppression of antitumor immunity in their mouse model [+PD-L1+ myeloid cells and enhancing effective T cell trafficking in contributing to the efficacy of PD-L1 blockade therapy [Collectively, these findings demonstrate that both tumor- and host-derived PD-L1 can play a critical role in inhibiting antitumor immunity, and the relative contribution of tumor- or host-derived PD-L1 is context-dependent. All the studies confirmed the role of PD-L1, either from tumors or host cells, in suppressing T cell functions, as evidenced by changes in cytotoxicity of effector T cells and the secretion of effector cytokines like IFNγ. However, these articles have different focuses on revealing mechanisms of PD-L1 in suppressing anti-tumor immunity. Noguchi et al. conclude that tumor-associated macrophages (TAMs) are the major host cell type that contributes PD-L1 in the sarcoma tumor model both quantitatively and temporally. In their study, while in vivo up-regulation of PD-L1 on T3 tumor cells was in a transient and time-dependent manner, PD-L1 expression on TAMs was retained for long period of time, and can be induced by CD4se model . Tang et therapy . The wor therapy .+ PD-L1+ innate myelolymphoblastoid effector cells (IMLECs) [+ PD-L1+ myeloid cells in contributing to the efficacy of PD-1/PD-L1 blockade therapy in some tumors [Taking together, these independent studies largely complement and validate each other. Their work extends the mechanisms of action of PD-1/PD-L1 blockade therapy into the tumor microenvironment, and largely supports the concept that PD-L1 acts as a molecular shield on both tumor cells and host immune cells to prevent tumors from cytolysis by T cells. PD-L1 expressed on cancerous cells is not exclusively responsible for the therapeutic effect of PD-1/PD-L1 checkpoint blockade, whereas PD-L1 on both malignant cells and immune cells works concretely to functionally modulate the CTLs in the tumor microenvironment Fig. . Therefo(IMLECs) . It is we tumors , 8. Ther


When making financial decisions bank customers are confronted with two types of uncertainty: first, return on investments is uncertain and there is a risk of losing money. Second, customers cannot be certain about their financial advisor’s true intentions. This might decrease customers’ willingness to cooperate with advisors. However, the uncertainty management model and fairness heuristic theory predict that in uncertain situations customers are willing to cooperate with financial advisors when they perceive fairness. In the current study, we investigated how perceived fairness in the twofold uncertain situations increased people’s intended future cooperation with an advisor. We asked customers of financial consultancies about their experienced uncertainty regarding both the investment decision and the advisor’s intentions. Moreover, we asked them about their perceived fairness, as well as their intention to cooperate with the advisor in the future. A three-way moderation analysis showed that customers who faced high uncertainty regarding the investment decision and high uncertainty regarding the advisor’s true intentions indicated the lowest intended cooperation with the advisor but high fairness increased their cooperation. Interestingly, when people were only uncertain about the advisor’s intentions (but certain about the decision) they indicated less cooperation than when they were only uncertain about the decision (but certain about the advisor’s intentions). A mediated moderation analysis revealed that this relationship was explained by customers’ lower trust in their advisors. Ninety-four-year-old Mrs X, whose cognitive and physical abilities are impaired by old age, received a sizeable amount of money from her disbursed life insurance. To reduce her uncertainty on how to reinvest the money, she consulted a financial advisor. The advisor recommended that the “optimal” solution was to put her money in a long-term investment—obviously not considering Mrs X’s age . Thus, oUncertainty is experienced when people feel unable to predict future events or when they feel inconsistencies between important cognitions, experiences, or behaviors . UncertaOne way to cope with uncertainty about one’s decisions is to look for advice , clients also have to cope with uncertainty regarding the advisor (UnA).Accordingly, in situations where people are uncertain regarding their decisions, customers focus on cues allowing them to gain the needed confidence for their decisions. However, in financial consultancies, people do not only have to cope with uncertainty regarding the decision but also regarding the advisor’s true intentions either to support the client or to pursue self-interest. Therefore, in addition to having to cope with Uncertainty regarding the advisor refers to the difficulty to identify his/her true intentions. Usually, the financial advisor possesses information and knowledge that the client lacks. The lack of knowledge makes it difficult for the client to assess whether the advisor is acting in the best interest of the client. According to Principal–Agent Theory , agents Knowing the advisor’s intentions is crucial to the client’s continued reliance on the advisor . A studyTo find answers to this question, we build on two theoretical models from justice research – the Uncertainty Management Model (UMM) and the Fairness Heuristic Theory FHT,  which miThe Uncertainty Management Model  describeThe Fairness Heuristic Theory  explainsBank customers are in uncertain situations and do not know if they can trust their advisor. To investigate how people cope with such uncertainty we tested – based on the UMM and FHT – whether uncertainty increases people’s sensitivity to fairness cues and increase their willingness to cooperate with financial advisors regarding their investment decisions.1): the distribution of resources . Our participants were either approached in a shopping mall when the University of Salzburg was having a public event there or via the experimenter’s social networks. All participants were asked to fill out a questionnaire in which they had to think about their financial service providers and indicated their agreement to several items on a scale from 1  to 6 (= completely).Two-hundred and forty-two participants answered our questionnaire. Due to missing data on the scales cooperation intention, UnA, and trust, we had to exclude nine participants, leaving us with a final sample of 233 This measure focused on the uncertainty about investment decisions . Five items asked about the success of the participants’ investment .Participants were asked to think about the behavior of their financial advisor and describe his/her behavior with the help of the following items: the strategic behavior scale covered the three agency problems described above . For further analyses we combined the subscales to produce a general uncertainty scale about the advisor .5 was excluded. Procedural fairness was assessed with eight items . Distributive fairness was represented with three items . Informational fairness was measured with seven items  and interpersonal fairness with four items . In the following calculations we combined these subscales to a general fairness scale .Participants evaluated their advisor’s fairness behavior with items from the German version  of the O6; see complete questionnaire in the appendix).Trust in the financial advisor was measured with items from a questionnaire designed by Table 1.7This scale measured the intention of the participants to further use the consulting services of the current financial advisor . For the means, standard deviations, and intercorrelations of all measured variables, see According to the two theoretical models dealing with uncertainty—UMM  and FHT We conducted a multiple regression including three continuous predictors , and all of their interactions regarding the dependent variable intention to cooperate ; Model 3SE = 0.06, t(225) = -2.65, p = 0.009, [95% CI: -0.29 to -0.04]), UnA  = -8.37, p < 0.001, [95% CI: -0.72 to -0.45]), and perceived fairness  = 3.36, p = 0.001, [95% CI: 0.11 to 0.40]) indicating that all three variables  decreased people’s cooperation intentions.The analysis revealed significant main effects of UnD  = -2.19, p = 0.030, [95% CI: -0.11 to -0.01]. Simple slopes indicated that when UnA and UnD were low, high and low fairness did not make a difference regarding people’s intentions to cooperate (p = 0.773). However, when any kind of uncertainty was involved (high UnA or/and high UnD), high fairness led to more cooperation intentions than low fairness . Furthermore, when both uncertainties were high, people had the lowest intentions to cooperate in both the low and high fairness conditions .In addition and most importantly, the three-way interaction between UnA, UnD, and fairness was significant, β = -0.06, ps < 0.001). In contrast, high UnD (compared to low UnD) led to lower cooperation when UnA was high and fairness low (p = 0.023). See Table 2 for a summary.Moreover, the regression weights show that the weight for UnA was higher than for UnD. This suggests that UnA had a larger impact on client’s cooperation intentions than UnD. In all conditions, whether fairness and/or UnD were high or low, high UnA always led to lower cooperation intentions than low UnA  = -2.19, p = 0.030; distributive fairness × UnA × UnD, β = -0.05, SE = 0.03, t(225) = -1.78, p = 0.076; interpersonal fairness × UnA × UnD, β = -0.06, SE = 0.03, t(225) = -1.67, p = 0.096; see Tables 6). This suggests that especially procedural fairness is important to compensate for the uncertainties.Additionally, we performed separate moderation analyses for the four fairness dimensions and found significant three-way interactions for the procedural fairness dimension, and marginal significant three-way interactions for the distributive and interpersonal fairness dimensions, all pointing into the same direction  = 1.97, p = 0.050, [95% CI: 0.00 to 0.12]. Trust had a significant effect on cooperation intentions, β = 0.25, SE = 0.06, t(230) = 4.12, p < 0.001, [95% CI: 0.13 to 0.37]. The direct effect of UnA on cooperation intentions was significant as well, β = -0.67, SE = 0.06, t(225) = -11.09, p < 0.001, [95% CI: -0.79 to -0.55].We conducted a mediated moderation analysis using PROCESS SPSS macro  and perceive low fairness, trust in the advisor does no longer seem to be involved in the process between UnA and intention to cooperate.For the slopes, we found that trust mediated the conditional indirect effect of UnA on cooperation when UnD was high and fairness was low, β = -0.13, We opened this paper by referring to the dilemma faced by financial consulting customers. On the one hand, customers want and need advice to reduce uncertainty regarding their risky decisions. On the other hand, they have to deal with uncertainty regarding the advisor’s true intentions, i.e., whether they pursue their own interests instead of the clients’ best interests. This dilemma describes two different forms of uncertainty: uncertainty regarding investment decisions and uncertainty regarding the advisor’s intentions. The current study examined customers’ intended future cooperation with an advisor when they were facing these two forms of uncertainty. Furthermore, as research has shown that in uncertain situations people need cues to regain their confidence, we introduced fairness as an important predictor for cooperation in consultancies.We based our study on the UMM and the FHT predicting that people react more strongly to fair treatment when uncertainty salience is high. Therefore, we suggested that perceived fairness is important when any uncertainty is high and especially important when both uncertainties are high. In the present study we asked participants to think about their experiences with “saving and investing money,” assessed their uncertainty regarding the decision and regarding the advisor’s intention, and their perception of fairness in the consultancy. Our findings indicated that whenever people were uncertain in a consultancy, whether uncertain about the decision or/and advisor, their intentions to cooperate with the advisor increased with perceived fairness. Moreover, both uncertainties together led to the lowest intentions to cooperate.Interestingly, a higher regression weight for UnA than for UnD indicated that in our study, UnA had a larger impact on client’s cooperation intentions than UnD. Thus, high UnA seems to be most costly for financial advisors regarding the customers’ intention to cooperate in the future. High experienced UnA seems to be especially detrimental for the relationship between the financial advisor and his/her customer. What changes in the relationship between customers and their advisors when they are confronted with uncertainty regarding the advisor’s intention, i.e., when people face the risk of being exploited by their advisor? The mediation analysis suggests that trust can help to explain this process: because clients mistrust that their advisors act in the client’s best interest and instead pursue their own goals, they refrain from cooperating with the advisor. However, if people want to work together in interdependent relationships, they need to trust each other . If custIn the current article, we have introduced fairness as a crucial cue in uncertain consultancies. Fairness is a cue displayed in the social interaction itself and thus differs from variables such as the advisor’s expertise or confidence which stem from the classic Judge-Advisor Research  or authority-oriented based situations (FHT). The current results expanded this line of reasoning by taking into account both uncertainties together and found that both are important in explaining cooperation intentions but that uncertainty regarding the advisor was more influential. However, they did not reinforce each other. This might be different in other consultancy situations. For example in health-related contexts – when people ask themselves what the best decision is and whether they can trust their advisors but they are anxiously aroused because they worry about their health – cues that induce mistrust might lead to overreactions. A potential mediator in this situation might be perceived loss of control. In future research, it would be fruitful to investigate the influence of different kinds of uncertainties and their relationship in various advisor–client interactions and to shed light on relevant mediators.Resulting from the economic crisis, people seem to be highly aware of both types of uncertainty (UnA and UnD) and even more vigilant to advisor’s trustworthiness. Therefore, since then, bank customers may evaluate the financial consultancy through the eyes of uncertainty. Consequently, it is important for banks to develop strategies that help their customers overcome this uncertainty. Our findings suggest that fair treatment might be such a strategy. Fairness increased people’s intentions to cooperate even when uncertainty was high. Nevertheless, it is essential to not understand fairness as a substitute which can easily eliminate people’s uncertainty. Rather, our findings indicated the lowest willingness to cooperate with the advisor when UnA and UnD was high. Fairness slightly improved the willingness but did not set people’s willingness back to baseline (when there was no uncertainty present). Thus, the way how advisors treat their customers and explain their products is critical and should not be neglected in the day-to-day running of a financial business. Fair treatment during consultancy is one way to help customers to reduce uncertainty and regain trust in their financial advisors.An advantage and disadvantage at the same time is that we collected our data in the field. On the one hand, a limitation of our research is that we could not control for further variables , on the other hand and at the same time it may be an advantage because we were able to directly examine how people cope with the insecure situation after the economic crisis. Moreover, manipulating a general uncertainty (UMM) and personal uncertainty (FHT) independently of each other in the laboratory could have helped to understand the interplay between different types of uncertainty and the role of fairness in this interplay. It would be important for future research to investigate different types of uncertainty in combination with the risk of losing real money  in the controlled environment of the laboratory. For future research it would also be interesting to investigate the long-term process of uncertainty and the reconstruction of trust in the advisor. Uncertainty regarding the advisor’s intentions might lead to mistrust, and fair treatment might be a way to regain trust. We are aware that we only measured people’s intention to cooperate in the future with the advisor, which is not the same as real behavior. Nevertheless, we believe that future studies might benefit from our findings and we hope that researchers further investigate the positive effect of fairness on cooperation in uncertain financial conditions.Uncertainties are part of our daily lives and especially part of our social interactions. In particular in financial consultancies, where uncertainty regarding an investment decision and uncertainty regarding the advisor’s intentions are high, we need cues helping us to deal with those uncertainties. We identified fairness as one cue helping people to compensate for uncertainty. Furthermore, our results indicate that customers’ uncertainty about the advisor is most costly for the customers’ intention to cooperate in future. However, our further analysis could identify loss of trust as a mediator, which can explain why customers facing high uncertainty about the advisor are not willing anymore to cooperate with their financial advisor.We are grateful to Barbara Grall for helping in the data collection and to Thomas Scherndl for his statistical advice.Although this study used human subjects, the approval of an ethical committee does not seemed necessary. The study was only about non-intrusive issues.BM and EJ developed together the research question, hypothesis and the research design. BM and CM did mainly the data analysis; together we did the writing of the manuscript.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.


Despite U.S. mothers’ wide adoption of pumps and bottles to provide human milk (HM) to their infants, mothers lack comprehensive, evidence-based guidelines for these practices. Thus, some women use online sources to seek information from each other. We aimed to characterize the information women sought online about pumping. We used data provided by ~25,000 women in an open cohort within a discussion forum about parenting. We examined 543 posts containing questions about providing pumped HM cross-sectionally and longitudinally in three time intervals: prenatal, 0 through 1.5 months postpartum, and 1.5 to 4.5 months postpartum. We used thematic analysis with Atlas.ti to analyze the content of posts. During pregnancy, women commonly asked questions about how and where to obtain pumps, both out-of-pocket and through insurance policies. Between 0–1.5 months postpartum, many mothers asked about how to handle pumped HM to ensure its safety as fed. Between 1.5–4.5 months postpartum, mothers sought strategies to overcome constraints to pumping both at home and at work and also asked about stopping pumping and providing their milk. Women’s questions related to ensuring the safety of pumped HM represent information women need from health professionals, while their questions related to obtaining pumps suggest that women may benefit from clearer guidelines from their insurance providers. The difficulties women face at home and at work identify avenues through which families and employers can support women to meet their goals for providing HM. In the United States, mothers whose infants are fed human milk (HM) have rapidly and widely adopted using pumps and bottles to provide HM in place of some or all feeding at the breast . Of the Because of mothers’ need or desire to work outside the home in their first postpartum year ,16,17,18The impetus for this work is that, in the absence of comprehensive, evidence-based guidelines for pumping and providing pumped HM, and without the benefit of generational knowledge and influence that may be available with feeding at the breast , women mWe aimed to characterize the information women sought over time about pumping on an online parenting discussion forum. The information women seek from each other may represent information that is not currently accessible to them from professional resources, and understanding their questions will provide knowledge of the information needed to better support women in their practices of pumping and providing HM.We conducted a qualitative, longitudinal and cross-sectional analysis of data provided by a cohort of women within an online discussion forum whose infants were born in April 2014. We used BabyCenter , one of To investigate how the number and nature of questions changed over time, we examined questions women asked about pumping for three age groups: when women were pregnant, from delivery through 1.5 months postpartum, and from 1.5 to 4.5 months postpartum. These infant age groups were chosen to reflect prior analyses of the IFPS II by others , who divPrevious qualitative work  has idenThe unit of analysis was publicly accessible posts on BabyCenter forums  that incWe identified posts to be examined for inclusion in analyses using relevant keywords such as “pump”, “pumping”, and “expressing”. We saved all posts about pumping from the web as PDF files. Posts were divided in the three infant age groups, according to the date of the post . Inasmuch as the majority of the women did not include their infants’ due dates or ages in their posts, we assumed a mean sample due date of 15 April 2014. We then used 1 April 2014 as a reference point for infants’ birth dates in this sample, as the median length of pregnancy in the U.S. is about two weeks short of full term . Thus, tThroughout the sorting process, some posts were excluded from analyses. We excluded posts that did not include questions (n = 21), such as those that were sharing information about pumping but not as a question. We also excluded posts in which the question was not about pumping or providing pumped HM (n = 21), and general, non-informative questions about pumping or providing pumped HM (n = 11). Non-informative posts included questions and polls that asked about others’ general opinions on pumping and providing pumped HM instead of a specific aspect of these practices. The inclusion of data into analyses is described in Included posts were examined with a thematic analysis using open- and closed-coding in Atlas.ti . Primary analysis was done by a single coder (RY), using the code book created by JPF for prior qualitative work , and modThe April 2014 Birth Club had 18,303 members at the beginning of the data collection period and steadily grew through 4.5 months postpartum. Women in the April 2014 Birth Club posted 543 eligible questions, which were grouped by theme and infant age group . Women aWomen’s questions related to strategies for and difficulties with pumping were similar, whether they were asking about pumping at home, away from home, or both. As a result, findings from this theme, and those related to integrating pumping into work, were grouped together. Examples of topics raised by women whose posts were analyzed are listed in Women commonly asked questions about choosing pumps in the prenatal period, with some describing a desire to obtain their pumps before they delivered their infants or concerns that their insurance policies would not provide pumps until after they delivered. Before they delivered their infants, women also asked about how long it would take to obtain a pump through their insurance policies, and, thus, when they should start the process so as to receive a pump by the time they planned to use it.Questions about obtaining pumps indicated that women commonly purchased pumps out-of-pocket or through their insurance policies. Women who asked about purchasing a pump out-of-pocket either did not have an insurance policy that covered a pump or were unsatisfied with the pumps covered by their insurance policies. Some of the women who planned to purchase a pump out-of-pocket asked about how and where to obtain an affordable pump.I really want to get a breast pump but there just so expensive i’ve looked online and my [husband] is just like no thats to much but ive really want to get one until i seen the prices! Any one know of a good cheaper place to get them? Cus 200+ is just to much!—prenatalSome women whose insurance policies covered the purchase of a pump asked about which brands and models were offered by their policies, and about the processes by which they could obtain a pump through their policy. For example, some asked whether a doctor’s prescription was needed and whether and how they should obtain a pump from a special vendor.[Insurance provider] told me insurance would cover a breast pump. Well fast forward & I’m just a couple of days away from delivery & need to get mine ASAP. Has anyone with the same plan been able to pick up the pump from a med supply store? Are they shipped only? And did you need to get a prescription first?—prenatalMost questions about storing and preparing pumped HM were posted after mothers delivered their infants. Questions they asked in the prenatal period related to selecting supplies, such as bags and bottles to store and feed HM. In some of these questions, women described considerations, such as the maintenance required to keep supplies clean. In contrast, questions they asked after delivery commonly related to storing and preparing pumped HM that was safe for their infants .Mothers sought information about how to safely store their pumped HM, such as where, how, and in what containers to store their milk until it was fed. For example, they asked about how long pumped HM could be kept at room temperature or stored in the refrigerator or freezer: “How long do you store in the fridge? 5 days is the max? Then do you freeze the milk in bags?” (0–1.5 months postpartum). Some mothers asked whether it was safe for their infants to be fed milk that was stored and/or prepared by combining HM from different pumping sessions: “I am pumping after I feed and only getting about an ounce or less and would like to get to at least 4 if im freezing it. Can i combine??” (0–1.5 months postpartum).Mothers also sought information about how to safely prepare their pumped HM to be fed. They asked if infants should be fed fresh milk instead of frozen milk to ensure the safety of the milk, while describing that they did not want to waste their stock of frozen milk by providing only fresh milk. Mothers also asked whether bottled HM that had been refused or unfinished by their infants was safe to be fed to their infants later: “Is it safe once he starts drinking out of one bottle and he doesn’t finish all of it to save the rest in the fridge and give it to him at the next feeding?” (0–1.5 months postpartum). Further, mothers asked about the effect of consuming alcohol, caffeine, or medications on the safety of their milk. Some asked if they should pump and discard after consumption, and if so, for how long to do it to ensure the safety of the pumped HM as fed.Some questions focused on whether or not and how mothers could recognize the safety or nutritional value of their pumped HM by its taste, smell, and appearance. For example, some mothers asked how to interpret changes to the smell or taste of their pumped HM after refrigeration and freezing.I usually store the milk in the fridge for a couple of days and then freeze it if its not consumed…I noticed/tasted milk freshly expressed – it has a sweet taste. Milk stored in fridge, then in the freezer, when unfrozen, it seems slight acidic. Is this normal? [sic]—postpartum (1.5–4.5 months)Other mothers asked how to interpret the appearance of their pumped HM: “[My breast milk] has the thinnest layer of creamy hind milk on top after it’s been in the fridge for a while and separated. What’s up with that? I think it should be fattier,” (1.5–4.5 months postpartum).Mothers posted most questions about strategies for and difficulties with pumping between 0–1.5 months postpartum, when they were first attempting to pump. However, mothers asked most questions about pumping at work outside the home between 1.5–4.5 months postpartum, when they were preparing to, or had already, returned to work.Many questions related to strategies for and difficulties with pumping came from mothers who were transitioning from primarily feeding at the breast to pumping regularly. Mothers commonly indicated that this transition was in response to or in preparation for returning to work. Some mothers asked for advice about overcoming physical difficulties, such as nipple pain or bleeding from using pumps or engorgement from not pumping enough. Some mothers had already unsuccessfully tried other strategies for these problems. It seems like everyday my breasts get fuller, and never empty…I’ve tried heating pads, but only helped for a few pumps. Today my breasts are so sore, my nipples are cracked even though I use lanolin before and after pumping. Any suggestions?—postpartum (0–1.5 months)Other mothers had questions about or difficulties with their pumps, and sought information about using pump features and fixing pump malfunctions.Some of the mothers’ questions related to the barriers to pumping that they either experienced or anticipated. These barriers included the presence of infants who needed care, workloads that were heavy or inflexible, a lack of designated place to pump, and travel: “How do you handle meetings (both in and out office) and pumping? I’m more worried about a few all day meetings I have off-site. Do you bring your pump with you?” (1.5–4.5 months postpartum).Mothers only posted questions about stopping pumping in the postpartum period, and most often between 1.5–4.5 months postpartum.In their questions about stopping pumping, mothers described a number of considerations, including their infants’ age, their own emotional and physical burdens related to pumping, and how important it was to them to provide HM.Some mothers described reasons for stopping pumping, such as feeling burdened from the additional tasks of pumping, and asked questions related to whether those reasons were appropriate or acceptable. Some mothers were generally interested in what others were doing or planned to do, or asked for advice on when they should plan to stop pumping.When will you stop pumping? …I guess I’m not sure what my end goal should be. A certain age? A certain amount frozen? What is your situation, how long will you pump for? Maybe hearing others situations will help me decide what I want to do.—postpartum (0–1.5 months)Some posts about stopping pumping were related to the mothers’ personal experiences with stopping or transitioning away from pumping. Some mothers asked general questions about this experience, while others asked questions about specific challenges they anticipated related to stopping pumping, such as guilt.I have been exclusively pumping since day 1 and [my baby] is now 16 weeks old. For various reasons I am ready to give up on pumping and put him on formula. However, how do I deal with the guilt of now doing something that feels right for me instead of what’s obviously best for him?! Pumping is tiresome, I find it very hard to do other things like make healthy lunches for myself for example, and I’m going nuts with constantly washing and storing the paraphernalia.—postpartum Even though some mothers were themselves ready to stop pumping, they described difficulties related to family members who wanted them to continue to pump.I am mentally and physically exhausted from the strenuous schedule of pumping and taking care of a newborn. I return to work in one week and don’t want to stress about pumping there. Not to mention physically I am fed up [with] having boobs that weigh a million pounds, sweat, and hurt when I don’t pump every 2 to 3 h, specifically if I try to sleep longer. [My husband] wants me to continue to pump [because] he feels like the benefits outweigh all the physical, mental and emotional stresses I’m going thru. What would You do?—postpartum Some mothers reported or anticipated physical discomfort  that would result from stopping pumping and asked for advice on how to manage it. Both mothers who experienced and anticipated this discomfort asked how long it typically took for HM supply to dry up. Mothers who anticipated this discomfort in the future asked whether weaning gradually or all at once would lead to less pain.The findings presented here provide the first detailed insights into the information women seek from each other online about pumping and providing pumped HM. In this work, we identified a range of questions asked by pregnant and lactating women about these practices, which are paraphrased in Our findings highlight the need for comprehensive, evidence-based best practice guidelines for safe storage and preparation of pumped HM. Previous research has shown that the additional handling involved in pumping, storing, and preparing pumped HM may increase the risks of infant infections ,25. In tThere is also an indication of a need for clearer guidelines from insurance providers on how to obtain pumps as well as earlier access to pumps. In this study, we observed that many women relied on their health insurance policies to obtain pumps. However, women asked a range of questions about how and where they could obtain pumps, which suggests that they need guidelines on this process that are more understandable and readily available. Furthermore, the frequency of these questions in the prenatal period suggests that some women may prefer and benefit from earlier access to pumps from their insurance providers. Previous research suggests that, for mothers of very low-birth-weight infants, pumping in the first hour postpartum is important to mothers’ long-term HM output ,27. The Many of the mothers on BabyCenter reported feeling emotionally burdened by pumping in the early postpartum period, which suggests that mothers may benefit from more support from their partners and families. Social support, such as education about breast pumps from friends and relatives, is positively associated with longer durations of feeding HM . MothersMothers on BabyCenter also reported obstacles specific to pumping at work, which indicate that they may benefit from more support from employers and coworkers in managing and reducing such obstacles. These obstacles, such as inflexible work arrangements and lack of a designated place to pump, may explain, in part, why working IFPS II mothers who only pumped at work stopped feeding HM earlier than mothers who also, or only, fed their infants at the breast at work ,19. ThusThe qualitative work described here is not without its limitations. First, the sample of posts came from an open group of women whose demographic characteristics are unidentified, so the findings may not be generalizable to the larger population. For example, the analyses may not have captured the knowledge sought by women of lower income, who may not have access to the Internet or smartphones. Second, some posts on BabyCenter were randomly and irretrievably removed from forums for unspecified reasons and, as such, it is likely that some posts related to pumping and providing pumped HM were not collected. However, we gathered data every other day until the end of data collection period to reduce the number of missed posts. Third, when dividing posts into three intervals, we assumed that all infants in the April 2014 Birth Club were born on April 1, 2014. Thus, some questions may have been grouped in the incorrect postpartum interval, introducing unknown bias into the tally of questions in each interval. However, we expect such misclassification to be minimal in the prenatal and 0–1.5 months intervals, as many mothers indicated whether they were still pregnant or had recently delivered. Moreover, we do not anticipate that this limitation materially impacted the content or reliability of these findings. Finally, we did not analyze the responses to the women’s questions. Thus, the knowledge exchanged among mothers through their responses is an area of interest for further research. This work also has several strengths. First, the study methods and analyses were informed by analyses of IFPS II data  and by fThe findings presented here illustrate a wide range of information that women sought on social media about pumping and providing pumped HM to their infants. This information may represent what women are not receiving from their health professionals or insurance providers. This information may also suggest modifiable constraints to women’s practices for pumping and providing their milk. The questions women asked about how to safely store and prepare their pumped HM indicate their need for comprehensive, evidence-based guidelines for these practices. Furthermore, these findings highlight that mothers and their infants may benefit from early receipt of pumps and access to clearer guidelines from insurance providers on how to obtain pumps. Finally, this study highlights the difficulties women face in attempting to pump their milk at home and at work and, thus, identifies potential avenues through which families and employers may help women meet their goals for pumping and providing HM.