HIGHLY CONDUCTING AND STRONGLY ADHERING POLYPYRROLE COATING LAYERS DEPOSITED ON GLASS SUBSTRATES BY A CHEMICAL PROCESS

To improve adhesion between polypyrrole and glass, new pyrrole-substit uted organotrialkoxysilanes coupling agents are synthesized and studie d. Solubility, hydrolysis, and self-condensation features in aqueous s olutions are investigated by IR, H-1, and Si-29 NMR spectroscopies. Va rying the experimental conditions of pyrrole chemical polymerization o n glass fibers surfaces indicates that a preliminary substrate treatme nt with these coupling agents and the use of a chemical vapor depositi on process jointly lead to very thin (around 50 nm) polypyrrole layers with a particularly even and homogeneous aspect and adhering perfectl y to glass surfaces. This last point has been plainly demonstrated by pull-out tests on conductive fibers embedded in resin and by tensile p ull-off tests on silica plates. An unexpected effect of the use of spe cific silanes, when compared to commercial coupling agents, is an enha ncement of polypyrrole conductivity (typically 150-200 S/cm), which ca n be related to the high regularity of the deposit.