Reinforced Mechanical Properties and Tunable Biodegradability in Nanoporous Cellulose Gels: Poly(L lactide co caprolactone) Nanocomposites.
Incorporation of nanofillers into aliphatic polyesters is a convenient approach to create new nanomaterials with significantly reinforced mechanical properties compared to the neat polymers or conventional composites. Nanoporous cellulose gels (NCG) prepared from aqueous alkali hydroxide/urea solutions can act as alternative reinforcement nanomaterials for polymers with improved mechanical properties. We report a simple and versatile process for the fabrication of NCG/poly(L lactide co caprolactone) (NCG/P(LLA co CL) nanocomposites through in situ ring opening polymerization of L lactide (LLA) and e caprolactone (e CL) monomers in the NCG. The volume fraction of the NCG in the nanocomposites was tunable and ranged from 4.5% to 37% Fourier transform infrared (FT IR) X ray diffraction (XRD) and differential scanning calorimetry (DSC) results indicated that P(LLA co CL) were synthesized within the NCG and partially grafted onto the surface of the cellulose nanofibrils. The glass transition temperature (Tg) of the NCG/P(LLA co CL) nanocomposites could be altered by varying the molar ratio of LLA/e CL and was affected by the volume fraction of NCG. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images confirmed that the interconnected nanofibrillar cellulose network structure of the NCG was finely distributed and preserved in the P(LLA co CL) matrix after polymerization. The dynamic mechanical analysis (DMA) results showed remarkable reinforcement of the tensile storage modulus (E' of the P(LLA co CL) nanocomposites in the presence of NCG, especially above the Tg of the P(LLA co CL) The modified percolation model agreed well with the mechanical properties of the NCG/P(LLA co CL) nanocomposites. The introduction of NCG into the P(LLA co CL) matrix improved the mechanical properties and thermal stability of the NCG/P(LLA co CL) nanocomposites. Moreover, the NCG/P(LLA co CL) nanocomposites have tunable biodegradability and biocompatibility and potential applications in tissue engineering repair, biomedical implants, and packing.
Biomacromolecules