Fabrication And Tribological Properties Of Organic-inorganic Self-lubricating Microcapsules

Inorganic-covered polymer microspheres with well-defined structure have attracted increasing interests because they have many potential applications such as delivery system,photonic crystals and functional materials.Organic/inorganic hybrid shell microcapsules can be synthesized by many methods.Afterwards,Pickering emulsions has been confirmed to be an ideal method for fabricating organic/inorganic hybrid microcapsules owing to low toxicity because of surfactant-free,low emulsifier content,adjustable droplet size and excellent stability of emulsion.In this article,polysulfone/SiO₂?PSF/SiO₂?hybrid shell and PSF/SiO₂ hybrid shell microcapsules loaded with lubricant oil as core materials were prepared via the Pickering emulsions polymerization and Pickering emulsions-solvent evaporation technology.The main contents can be summarized as the following:?1?In this section,facile and efficient encapsulation of lubricant oil in SiO₂-Wrapped PS microcapsules are accomplished by Pickering polymerization technique.The Triton X-100-IPTS?T-IPTS?fumed SiO₂ nanoparticles were used as emulsifiers for the formation of O/W Pickering emulsions and the stability factor of Pickering emulsions was investigated.The as-obtained microcapsules were characterized by scanning electron microscope?SEM?,thermogravimetric analysis?TGA?,Fourier transform infrared spectra?FT-IR?and dynamic laser scattering?DLS?.These results suggest that the microcapsules display spherical shaped with core content of about 38.3%,the average diameter is 3.3?m,shell thickness is about 950 nm and outstanding thermal stability for lubricant oil with decomposition temperature of 250?.Moreover,the microcapsules are embedded into epoxy resin for self-lubricating coatings.Investigated by the frictional coefficient and wear test,the self-lubricating microcapsules-incorporated epoxy coatings on aluminum plate indicate excellent dispersibility of microcapsules in coatings and favourable antifriction effects.?2?Lubricant oil-filled polysulfone/SiO₂?PSF/SiO₂?hybrid shell microcapsules are prepared by the combination of Pickering emulsification and the solvent evaporation technique.Silica particles are used as stabilizers.The structure and properties of the microcapsules are influenced by the silica particle concentration,agitation speed,and encapsulation temperature.The formation of PSF/SiO₂ hybrid microcapsules is confirmed by scanning electron microscope?SEM?,Fourier transform infrared spectroscopy?FTIR?,and thermal gravimetric analysis?TGA?.The resulting microcapsules prepared at the optimum synthetic parameters show spherical,ideal structure with a rough outer surface,mean diameter of 5.0±0.6?m,shell thickness of 0.83?m,core content of 50.5 wt.%and excellent thermal stability with an initial evaporating temperature of 250?.The synthesized microcapsules are embedded into epoxy for application in self-lubricating composites.Investigated by friction and wear tests,the tribological properties of the self-lubricating microcapsules-incorporated epoxy composites obtain a significant improvement.