Preparation Of Super-hydrophobic Silica Films With Visible Transmission By Sol-gel Method

In the past few years,super-hydrophobic surfaces with water contact angleslarger than 150°have received a lot of research attention, due to their importa-nt applications ranging fromself-cleaning materials to microfluidic devices and b-iomaterials. Up to now, artificial superhydrophobic surfaces have been fabricat-ed by tailoring surf-ace topography and using techniques such as lithograph,las-er and plasma etching,physical and chemical vapor deposition,anodicoxidation, electrodeposition,sol-gel, electrospinning,layer-by-layer deposition,and others. However, either special equipment or complex process control is required in mo-st cases. As a consequence,it still remains a great challenge to develop simple andconvenient techniques for the fabrication of super-hydrophobic surfaces.In this dissertation,we report on a simple and super-hydrophobic surfaces. We have succeeded in the preparation of super-hydrophobic surfaces on the glasssubstrates.Super-hydrophobic silica-based thin films were prepared by means of sol-gel processing ,a phase separation and self-assembly(SA).Desired surface roughness was obtained by combining a sol HCl as a catalyst, a another sol NH4OH as acatalyst and a phase separation of tertraethyl orthosilicate (TEOS) induced by theaddition of poly(acrylic acid)(PAA). Morphology of the film surfaces was observ-ed with SEM and AFM. The results show: when polyacrylic acid molecular weight changes or its content does, the film morphology is different :A morphology of thin film with the high molecular weight polyacrylic acid:when polyacrylic acid content changes,the morphology of the films changes fromthe "volcano" consisting of nano-micr-pore to the"hills"appearance consisting of "groove" and "irregular hills ".Annother morphology of thin film with the high molecular weight polyacrylicacid: the surface morphology of the films is "crack" morphology from distribution of a large number of micro-cracks.Meanwhile, the film has a dual roughness. The "volcano", "Hills" or "crack" morphology form a large surface roughness, that is micro-roughness. The spherical nano-particles from the base Sol form a small surface roughness, or nano-roughness. It play a complementary role to micro-roughness.The interaction of micro- and nano-roughness to the surface is benefit to coat the air, and so reduce film surface jointly to make the films with high contact angle. After they were modified with the TMCS or SCA, the films change its wetting property and are hydrophobic.The adhesion of the film was measured by qualitatively with the tape and rubber tests. And the films were unaffected by the tape and the rubber tests. The high scratch resistance and super-hydrophobicity is a very promising result.