Abstract:
Hydrophobic coatings were prepared in xylene/ethyl acetate as solvent with fluorosiloxane-modified epoxy resin as the matrix. The impact of fluorosiloxane content and solvent type on hydrophobicity, as well as the micromorphology of the coatings were examined. The results showed that with the increase of fluorosiloxane content, the contact angle of the coating enhanced. When just xylene was used as the solvent, the surface of the coating was relatively smooth with a maximum contact angle of 105.0°. In the xylene/ethyl acetate system, 5~15 μm micropores were formed, which was due to the difference in solvent volatilization rate. Meanwhile, 0.1~0.6 μm bumps were generated in those micropores along with a phase separation of fluor siloxane and epoxy segments according to the nucleation-growth mechanism. The surface energy of coatings reduced with the spontaneous migration of F and Si to the outer surface during the process of film formation. When the mass fraction of fluorosiloxane segments increased to 30%, much more air could be trapped in the micropores and protrusions. This results in the contact angle of the coating being increased to about 115.5°, and the hydrophobicity was also largely improved. The coating also exhibits a high adhesion of 5B and hardness of 6H, suggesting its potential for real-world applications.