High Crystallinity Boron Nitride Nanosheets: Preparation and the Property of BNNSs/Polyvinyl Alcohol Composite Film

Abstract

A kind of hexagonal boron nitride nanosheets (BNNSs) with high crystallinity was synthesized using magnesium borate nanosheets with petal morphology as the template and boron source while ammonia as the nitride source. The morphology and structure of the BNNSs were analyzed by SEM, TEM, XRD, Raman, and FT-IR. The results show that the BNNSs are a kind of single crystalline h-BN with a thickness of about 5 nm and a diameter of 150-300 nm, respectively. The BNNSs aggregate together and inherit the petal shape of magnesium borate. Then, BNNSs/polyvinyl alcohol (PVA) composite films containing different content of BNNSs were prepared. The results show that elastic modulus of the film containing 30% BNNSs is 39.8% higher than that of pure PVA films, while the in-plane thermal diffusivity and thermal conductivity increase about 7 and 8 times, respectively, demonstrating the significant improvement to the thermal performance of PVA by adding this kind of BNNSs.