Preparation And Application Of Hexagonal Boron Nitride Nanocomposite Materials

Hexagonal boron nitride nanosheets?h-BNNSs?are a kind of typical two dimensional material and show less than 2%lattice mismatch with graphene.As a result,h-BNNSs share many common properties with graphene,such as outstanding mechanical strength,good optical property and high thermal conductivity.However,different from graphene,h-BNNSs also possess higher oxidation resistance and better chemical stability,making them promising in some harsh environment applications.In addition,with the rapid development of nanocomposites and the integration of the advantages of all the materials that make up the nanocomposites,the nanocomposites have better performance than the single materials.However,there are many chemical modification methods for preparation of compound functionalization of hexagonal boron nitride,including modification methods of hydroxyl groups?-OH?and amino groups?-NH₂?,as well as atomic doping and heterostructure.Modification of these groups can improve the dispersibility of nano-sheet,which is a major obstacle.Other physical modification methods include the preparation of low-dimensional porous structure,and the mechanical strength and other properties of the composite can be improved by improving its structure.In this paper,by selecting polyether block polyamide?Pebax?,polyvinylidene fluoride?PVDF?and hexaethylboron nitride nano-sheet for chemical/physical functionalization respectively,and respectively explore its application in friction and lubrication performance and oil-water separation,and obtain the following main research results:?1?In current report,solvent dispersible Pebax chemical functionalized h-BNNSs?Pebax-BNNSs?have been fabricated through a one-step no solvent mechanical exfoliation process.Pebax molecules will synchronously react with the dangling bonds formed during the exfoliation process to achieve in situ modification of h-BNNSs.The as-obtained Pebax-BNNSs have excellent dispersibility in water that can be used as lubricants.The reciprocating friction tests demonstrate such Pebax-BNNSs/water suspensions possess excellent antifriction and antiwear performance with low concentration of 0.3 mg/mL under atmospheric conditions.The friction coefficient can be as low as 0.003,achieving superlubricity.Further systematical investigation on the wear trace,wear debris and counter balls implies that the friction mechanism can be regarded as“dispersion-compensation and fill repairment”process.This result demonstrates that h-BNNSs can achieve superlubricity as water base lubricant additives via facile surface modification,making them promising candidates as lubricant additives for practical applications.?2?Porous composite filter films were prepared by solvent exchange and freeze-drying,using PVDF materials and h-BNNSs for physical functionalization?h-BNNS/PVDF?.It was found that the superhydrophobicity of PVDF membranes can be achieved by adding a small amount of h-BNNSs without affecting the superhydrophilic properties of PVDF during the preparation process.The excellent superhydrophobicity and superoleophilicity make these porous h-BNNS/PVDF composites to be promising candidates for separating oil and water as membranes in practical oil-polluted waste water treatment.