The influence of silica synthesis on the morphology of hydrophilic nanocomposite coating

A nanocomposite coating, based on Glycidioxypropyltrimethoxysilane and Aminoethylaminopropyltrimethoxysilane, was prepared using silica nano particles in a sol-gel process by the addition of silica suspension. The good level of adhesion was attributed to the formation of Si-O-Si bonds between the coating and the substrate. Moreover, another factor in improving adhesion was linked to the tendency of silica particles to form aggregates in the continuous phase. This morphology enhances the organic phase mobility of the coating, which leads to flexibility of the coating in stress support and improving adhesion. In order to evaluate the hypothesis, the relaxation properties of this coating were compared with those of a coating synthesized by in situ polymerization of tetramethoxysilane by means of Dynamic mechanical thermal analysis. The results proved the validity of the theory that silica particles of the coating prepared with silica suspension tend to form aggregates and produce particle-matrix morphology, which allows the organic phase to find further mobility. Scanning Electron Microscopy was employed to monitor the surface of the coating. The Atomic Force Microscopic technique was used to monitor the surface roughness of the coating. Transmission Electron Microscopy showed that the dimension of silica particles remains at nano scale.