Embedded polyhedral SiO2/castor oil-based WPU shell-core hybrid coating via self-assembly sol-gel process

Abstract

An embedded polyhedron SiO2/castor oil-based waterborne polyurethane (CWPU) shell-core hybrid coating was designed and successfully prepared via a self-assembly sol-gel process. The morphologies of the particles in hybrid emulsions and the dispersion stability of the emulsion as well as the surface, thermal, and mechanical properties of the hybrid films were characterized. The results showed that the introduction of 3-(methacryloxy)propyl trimethoxy silane (γ-MPS) contributed to the formation of nano-silica shells on the surface of CWPU colloidal particles and covalently connecting CWPU with silica in films. When the mass ratios of γ-MPS:tetraethyl orthosilicate (TEOS) were 1:0, 1:1 and 1:4, the shell-core hybrid structure could be observed in the TEM (transmission electron microscope) images. In addition, the introduction of silica component inhibited the aggregation of particles and retained the good dispersion stability of the emulsion. Besides, silica component also shifted the wettability of CWPU films and significantly improved water resistance, thermal and mechanical properties of the CWPU films.