Preparation Of PMMA-SiO₂ ,Epoxy-SiO₂ Composite Superhydrophobic Films And Investigation Of Wettability

Superhydrophobic polymer-matrix nanocomposite films with micro-nano hierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. The method can be widely applied to other polymers. Thus intrinsically hydrophilic poly(methyl methacrylate), denoted as PMMA, and epoxy resin were selected as the polymer matrices to prepare hydrophobic and even superhydrophobic nanocomposite films by doping with silica (SiO₂) nanoparticles. The main contents and research results are as follows:1. PMMA, a representative engineering plastic, was used as the polymer matrix to prepare superhydrophobic PMMA-SiO₂ nanocomposite films via spin-coating the suspension of hydrophobic SiO₂ nanoparticles dispersed in PMMA solution. The wetting behavior of PMMA-SiO₂ nanocomposite films was investigated in relation to the concentration of PMMA solution and the dosage of SiO₂ nanoparticles dispersed therein. The morphology and chemical composition of superhydrophobic PMMA-SiO₂ nanocomposite films were studied by means of scanning electron microscopy (SEM) and X-Ray photoelectron spectroscopy (XPS). It has been found that hydrophilic PMMA film can be transferred to superhydrophobic PMMA-SiO₂ nanocomposite film by properly adjusting the concentration of PMMA solution and dosage of SiO₂ nanoparticles. The formation of micro-nano hierarchical structure and incorporation of hydrophobic nano-SiO₂ result in superhydrophobicity of PMMA-SiO₂ nanocomposite films. Resultant PMMA-SiO₂ nanocomposite films have a static water contact angle of above 163°.2. Epoxy resin with good adhering performance was used as the matrix to fabricate epoxy resin-SiO₂ superhydrophobic composite films with good adhesion to the substrate. The morphology and wetting behavior of epoxy resin-SiO₂ composite films were studied. The friction and wear behavior of epoxy resin-SiO₂ superhydrophobic composite films was tested with a UMT-2 multifunctional micro-tribometer, and the wear mechanism was preliminarily discussed. It has been found that epoxy resin-SiO₂ composite films can be endowed with superhydrophobicity by properly adjusting the composition, relevant static water contact angle can be as much as 160o. In the meantime, epoxy resin-SiO₂ superhydrophobic composite films have a lower friction coefficient than pure epoxy resin, and their friction coefficient tends to decrease with increasing contact angle.