Preparation And Self-healing Property Of Super-hydrophobic Coatings Based On Polyacrylate And Polysiloxane System

Super-hydrophobic materials is a kind of biomimic functional materials with a wide application prospect. Super-hydrophobic materials with self-healing function is the key to its popularization and application.In this dissertation, three different kinds of superhydrophobic coatings, polyacrylate-vinyltriethoxysilane-silica(PEA-VTES-Si O2), polydimethylsiloxanevinyltriethoxysilane-silica(PDMS-VOS-Si O2) and polyacrylate-polydimethylsiloxane-silica(AA-PDMS-Si O2) were prepared by dip coating process.The preparation process, surface structure and properties were investigated by Fourier transform infrared spectroscopy(FT-IR), measurement of contact angle(CA), scanning electron microscopy(SEM) and thermalgravimetric analysis(TGA). Self-healing performance of the three kinds of superhydrophobic coatings after the destruction with air plasma were mainly investigated by X-ray micro analysis(EDX), X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM) and so on.Firstly, vinyltriethoxysilane(VTES) and Si O2 were introduced into a common UV-curing coating system(EAO, AA, TMPTA, TPO). Under the irradiation of UV, the double bonds of VTES were copolymerized with acrylate. After futher high temperature condensation, the PEA-VTES-Si O2 superhydrophobic coating was prepared. The Results showed that the condensation time has a significant impact on wettability of the coating, and after 4h of condensation, the coating contact angles were kept over 150°. As Si O2 content increased, the hydrophobicity of the coatings were improved. When adding 5 phr Si O2, the contact angle of the coating reached 151.4°.Secondly, a moisture curing PDMS-VOS-Si O2 superhydrophobic coating was prepared by one step dipping process through introducing a certain amount of Si O2 into n-hexane solution of H-PDMS. The results showed that the Si O2 content has a significant effect on the wetting property of the coating. When adding 50 phr Si O2, the contact angle is 150.2°.Finally, on the basis of the previous two chapters, the moisture curing system of PDMS was introduced into UV-curing AA-VTES-Si O2 system. By dip coating process and high temperature condensation, AA-PDMS-Si O2 superhydrophobic composite coating was prepared. The results showed that contact angle of the coating with the addition of 5phr Si O2 was 151.1 °.SEM results showed that three superhydrophobic coatings all have micro-nano scale roughness structure,which is necessary for superhydrophobic property.Three kinds of superhydrophobic coatings were treated by air plasma, and all of which were transformed from superhydrophobic state into superhydrophilic state. But in the process of further heat treatment, the recovery of these coatings are completely different. PEA-VTES-Si O2 coating could not be restored to hydrophobic state,PDMS-VOS-Si O2 coating can gradually partially recover hydrophobic performance, but cannot restore superhydrophobic state, and AA-PDMS-Si O2 coating can recover superhydrophobic property after heat treatment at different temperatures. After repeated process by plasma damage and heat treatment, superhydrophobicity of AA-PDMS-Si O2 coating can achieve many times of self-healing.The SEM, EDX and XPS results showed that, micro-nano hierarchical structure of the coating was still well maintained in the recovery process of plasma damage and heat treatment,but the surface chemical composition has changed significantly. The self-healing superhydrophobicity of AA-PDMS-Si O2 coating is either due to the migration of Si-O-Si chain segment of organic polysiloxane under the effect of heat in order to reduce the surface free energy,or may be due to the negative compatibility between organic polysiloxane and polyacrylate matrix.