Mechanical Hardness and Adhesion Property of Surface-Polymerized Nanocomposites based on Polyaniline and Sol-Gel Silica

Abstract

We have investigated the mechanical hardness and adhesion property of electrically conductive polyaniline (PANI) and polyaniline/silane composites prepared on a glass substrate by using a simple polymerization and deposition method. The formation of the conducting nanocomposites was verified by spectroscopic analyses and electron microscopy imaging. The polyaniline films formed in the presence of (3-aminopropyl)triethoxysilane (APTES) were observed to exhibit a remarkable enhancement in their hardness. The nanoindentation study showed that, as the concentration of APTES was increased from 0 to 66.7 wt%, the loading required for a displacement of 25 nm increased from 0.1 to 10.1 mu N. Improved adhesion was observed even after 10 peel-off test cycles using commercially available 3M tape. A comparison between the silane materials showed that APTES, owing to the presence of catalytic amine groups, formed more robust composites than tetraethyl orthosilicate (TEOS) under the given processing conditions. The results of our study demonstrate that mechanically rugged polyaniline/silane composite films can be used as pH sensors.