Preparation And Application Of High Thermal Conductive Boron Nitride Nanosheets By Template Method

Boron nitride nanosheets(BNNSs)as the most important III-V two-dimensional materials have many excellent properties such as high strength,high thermal conductivity,insulation,corrosion resistance,piezoelectric and biological compatibility,and have great potential applications in the high strength and functional composites,field emission transistors and other digital switch and the biomedical sciences.How to achieve the efficient and stable synthesis of BNNSs and reduce the cost as far as possible is the current research hot point.In this thesis,we synthesized BNNSs by choosing different template agent,and studied the composite material thermal properties used BNNSs as fillers for polymer thermoplastic polyurethane elastic polymer(TPU)and polyvinyl alcohol(PVA).A high crystallinity BNNSs with a thickness of ~7 nm was prepared by using biomass Bellamya Quadrate Shells(BQS)as a template.By adjusting the material ratio,the yield rate reached 86%.The unique multi-layer structure of BQS is suitable for the BNNSs growth.And the ammonia gas reacted with the surface of the template.BNNSs/TPU composite film prepared by the BNNSs was used for good mechanical and thermal properties.The high crystallinity BNNSs with the thickness of 1~2 nm and 1~3 nm was synthesized by using the common biomass templates of Egg Shell and Paphia Undulata Shell.It was found that the reaction time,atmosphere and temperature had an effect on the growth,morphology and structure of BNNSs.BNNSs/PVA composite films were prepared with good mechanical and thermal properties.A high crystallinity BNNSs with corresponding morphology of nano-flower was prepared with the specific morphology of the magnesium borate template and precursor.The boron nitride nano-flower can be dispersed as BNNSs by ultrasonic treatment.The flower-like structure of magnesium borate nanosheets is suitable for BNNSs growth.BNNSs/PVA composites prepared by BNNSs have good mechanical and thermal properties.