Use of aminosilane coupling agent in the synthesis of conducting, hybrid polypyrrole–silica gel particles

A new route for the synthesis of conducting polypyrrole–silica composites is described. Silica gel particles were modified by aminopropyltriethoxysilane (APS) and acted as porous inorganic substrates for the in situ synthesis of polypyrrole (PPy). The resulting polypyrrole–silica–APS hybrid materials were characterized by XPS, thermogravimetric analysis, BET and conductivity measurements. It is found that APS yields a substantial increase in the PPy mass loading (from 6 to 11.5 wt.%) but, more importantly, the hybrid particles obtained are conductive and have a negligible static charge in XPS due to their PPy-rich surfaces. In the absence of any APS treatment, polypyrrole is mainly loaded in the pores of the silica gel so these polypyrrole–silica particles are poorly conductive and charge up during XPS analysis. The conductivity threshold (10−2 S cm−1) was obtained for an APS initial concentration of 1% (v/v). In addition, these conducting hybrid particles have a fairly high specific surface area in the 160–180 m2 g−1 range. © 1998 John Wiley & Sons, Ltd.