HIGH MECHANICAL PERFORMANCE OF GRAPHENE OXIDEPOLY (VINYL ALCOHOL) LAYERED NANOCOMPOSITES

摘要

During recent several years, great efforts have been applied to graphene-based nanocomposites to achieve high mechanical performance. At low concentrations, graphene-based nanofillers have assuredly given rise to exceptional enhancements in mechanical properties. The factors referring to the significant improvements mainly include the well dispersion, the enhanced specific area and the two dimensional geometry of graphene, as well as the suitable interfacial adhesion. For example, a ~31% increase in tensile strength and a ~40% improvement of Young's modulus were achieved by addition of only 0.1 wt% of graphene nanosheets into epoxy nanocomposites. However, high concentration graphene-based nanofillers introduced into nanocomposites would lead to agglomerates, and thus restrain the further improvements of mechanical properties. A great deal of researches have been attempted to effectively transfer the outstanding mechanical performance of graphene-based nanosheets at high loadings and realize the ultrastrong nanocomposite materials. Layered PVA nanocompsite with high graphene oxide (GO) nanosheets loadings has been made by LBL technique, which exibited a enhancement of mechanical properties. In addition, by aqueous filtration, Park et al. prodced polyallylamine crosslinked GO layered nanocomposite with well mechanical performance. However, up to now, the modulus and strength of these composites are still much lower than the theoretically predicted values. And the structural factors affecting mechanical behaviors of these layered nanocomposites still need deeply investigated. Herein, GO-based paper-like nanocomposites with high mechanical performances were fabricated by vacuum-assisted self-assembly technique, in which the nanosheets component takes up the majority and acts as principal framework. To probe the structural factors, the effects of polymer molecular weight onto the mechanical properties of nanocomposites were carefully studied. Furthermore, based on the AFM analysis, we proposed two modes for the enhanced mechanical properties of GO-PVA nanocomposites.