Preparation Of GO Hybrid Wall Microcapsules And Tribological Properties Of Self-lubricating Composites

With the continuous development of science and technology,microcapsule self-lubricating composite materials have been more and more widely used,its main applications include self-lubricating bearings,self-lubricating cylinders,sliding plate materials and other fields.Microcapsule type self-lubricating material is the microcapsule containing lubricant embedded in the polymer matrix,the microcapsule rupture under the action of friction,the released lubricant forms a lubrication transfer film at the friction interface,so that the composite material has the self-lubricating performance.At present,most of the commonly used self-lubricating microcapsules use ordinary lubricating oil as the core material,but the thermal decomposition temperature is low,and the friction resistance is poor.Most of the wall materials are single component wall materials,which are brittle and fragile,which limits their further processing and application,and it is difficult to meet the purpose of reducing wear and resistance of modern high-performance resin matrix under high temperature,high pressure and high speed conditions.In order to solve the above problems of microcapsule,expand the microcapsules in the application of high performance polymer resin,this paper has good heat resistance performance of green lubricant ionic liquid as the core material,wall by doping in graphene oxide（GO）to the preparation of new type double-wall or multi-walled microcapsule,improve the thermal stability of microcapsule and the frictional resistance of the composite,Expand the application range of self-lubricating microcapsules.The main work of this article includes:（1）Using green efficient lubricant ionic liquid as core material,the[BMIm]BF₄@PU/GO double-walled microcapsule was prepared by Pickering emulsion method and in situ polymerization method.The morphology of the capsule was uniform and stable.The average diameter was 82±26μm,and the initial thermal decomposition temperature was 226℃.When heated to 800℃,the residual amount increased from 5%to26.6%.The above[BMIm]BF₄@PU/GO double-wall microcapsules were added into epoxy resin to synthesize polymer-based self-lubricating composites.The effects of self-lubricating microcapsules on friction coefficient and wear rate were investigated through friction and wear experiments.The results showed that:Under the experimental conditions of load of 1.0MPa and speed of 0.50 m/s,the friction coefficient of 15wt.%[BMIm]BF₄@PU/GO double-wall microcapsule is the most stable,but the wear reduction effect of20wt.%[BMIm]BF₄@PU/GO double-wall microcapsule is the best.Compared with pure EP material,the friction coefficient of 15wt.%[BMIm]BF₄@PU/GO double-wall microcapsule is the best.The friction coefficient and wear rate decreased by 75.41%and 98.61%,respectively.Compared with pure epoxy,the friction coefficient and wear rate of[BMIm]BF₄@PU single-wall microcapsules decreased by 75.41%and 96.40%,respectively.（2）With[BMIm]PF₆as core material and GO as Pickering emulsion,LBL method was used to prepare[BMIm]PF₆@GO hybrid multi-wall self-lubricating microcapsules by the interaction of PDA and GO.The results show that the best emulsifying effect can be achieved when the pH of GO Pickering emulsion is acidic,the emulsion concentration is 0.1 mg/m L,and the mass ratio of oil to water is 5%-7%.The capsules can be formed stably with an average diameter of 5-10μm.Compared with pure waterborne EP resin,the friction coefficient decreases by about 77%.