Hydrophobicity of Polyacrylate Emulsion Film Enhanced by Introduction of Nano-SiO₂ and Fluorine.

This study proposes to utilize modified Nano-SiO₂/fluorinated polyacrylate emulsion that was synthesized with a semi-continuous starved seed emulsion polymerization to improve the hydrophobicity, thermal stability, and UV-Vis absorption of polyacrylate emulsion film. To verify the proposed method, a series inspection had been conducted to investigate the features of the emulsion film. The morphological analysis indicated that Nano-SiO₂ was surrounded by a silane molecule after modification, which can efficiently prevent silica nanoparticles from aggregating. Fourier transform infrared spectra confirmed that modified SiO₂ and dodecafluoroheptyl methacrylate (DFMA) were successfully introduced to the copolymer latex. The particle size of latex increased with the introduction of modified Nano-SiO₂ and DFMA. UV-Vis absorption spectra revealed that modified silicon nanoparticles can improve the ultraviolet shielding effect obviously. X-ray photoelectron spectroscopy illustrated that the film⁻air interface was richer in fluorine than film section and the glass side. The contact angle of modified Nano-SiO₂/fluorinated polyacrylate emulsion containing 3 wt % DFMA was 112°, slightly lower than double that of polyacrylate emulsion, indicating composite emulsion films possess better hydrophobicity. These results suggest that introducing modified Nano-SiO₂ and fluorine into polyacrylate emulsion can significantly enhance the thermal stability of emulsion films.