Research On Preparation And Properties Of The Layered Assemblies Composite Of Boron Nitride Nanosheetes

As an inorganic material, boron nitride has four kinds of body modifications, including hexagonal boron nitride(h-BN), rhombohedral boron nitride(r-BN), cubic boron nitride(c-BN)and wurtzite boron nitride(w-BN). Due to the excellent mechanical properties, high thermal conductivity and good insulation properties, as a structural analogue of graphene, boron nitride have attracted ever-growing research interest in the pastfew years. Because of these excellent properties, the layered assemblies composites of boron nitride nanosheets film will bring some new highlights.Self-healing ability and elastic modulus of nanocomposites may seem mutually compromised because of their opposite dependence on the mobility of polymeric chains. Here we showed that boron nitride nanosheets(BNNSs) can simultaneously enhance these seemingly contradictory properties in layer-by-layer(LBL) assembled composite films. The introduction of BNNSs into polyvinyl alcohol/tannic acid exponential growing LBL films resulted in an increase of elastic modulus from 8.6±0.060 GPa to 12.9±0.450 GPa along with the much improved self- healing ability triggered by water(from partial recovery to fully healing). The simultaneous enhancement may be attributed to the unique hard-soft interface, which not only allows the effective load transfer but also the synchronous movement of BNNSs and polymers. By varying the experimental parameters such as the sizes of BNNSs, the molecular weight of polymers and the pH of water bath, a mechanism for explaining the improvement of self- healing performance was proposed taking account of both in-plan and out-of-plane polymer diffusions in the crack area. O ur study may allow a bett er understanding of the self-healing mechanism of exponential LBL assembled films and the fabrication of a broad spectrum of new composite materials with intriguing multiple parameters.