A low cost and facile preparation of hydrophobic silica films and powders by a solution-based process

Abstract

Super-hydrophobic surfaces with water contact angle (WCA) higher than 150° generated a lot of interests both in academic and in industry because of their self-cleaning functionality. Emphasis was given to the effect of pH value on the hydrophobic behavior of the obtained fi lms or powders. At fi rst, SiO 2 sols were prepared by diluted ammonia. We found that following the increase of pH value of sol from 8 to 9, WCAs of the obtained fi lms increased from 121.8° to 131.8°. Following the continued increase of the pH value of sol, precipitates began to appear and smooth fi lm could not be obtained. The WCAs of the obtained powders could reach 121.7°, and through modifying by TMCS could further increase to as high as 165° and the water sliding angle (WSA) was 2°. The results of SEM indicate that the hydrophobic properties of the powders without modifying by TMCS should be originated from the formation of nano/micron binary structure, i e, a micronscale diameter and a nano-scale surface roughness. In this work we provide a better solution to fabricate superhydrophobic silica coating surface with a simple method at low cost.

Double-layer modification of water-based aluminum with SiO2 and polyacrylic acid by sol-gel process and in situ polymerization

“…But low molecular inhibitors could not form dense protection structure and are easily affected by environment. The other is macromolecular inhibitor such as polyacrylic acid [11,12] , poly(methyl methacrylate) [13] , epoxy ester resins [14] , polypyrrole [15] and SiO 2 [16][17][18][19][20][21][22][23] . In situ polymerization could form dense layer to protect aluminum.…”