Preparation, surface chemistry, and electrical conductivity of novel silicon carbide/polypyrrole composites containing an anionic surfactant

Abstract

AbstractNovel silicon carbide/polypyrrole (SiC/PPy) conducting composites were prepared using silicon carbide as inorganic substrate in the presence or absence of an anionic surfactant, dodecylbenzenesulfonic acid (DBSA). The surface modification of SiC particles was performed in aqueous solution containing the anionic surfactant by oxidative polymerization of pyrrole using ferric chloride as oxidant. Ash content analysis was used to determine the mass loading of organic fraction in the SiC/PPy composites. Scanning electron microscopy showed the surface modification of SiC by PPy. The presence of PPy in the composites was confirmed by infrared spectroscopy. The small gradual red shift of the band of the stretching vibrations of SiCO and SiOSi bonds and more intensive of PPy spectrum were observed when DBSA was used for composite preparation. The presence of both polypyrrole and surfactant was also detected by their respective N1s and S2p core level peaks recorded by X‐ray photoelectron spectroscopy. The electrical conductivity of SiC‐DBSA/PPy composites depends on PPy content at the surface and on pyrrole/DBSA molar ratio. The DBSA‐containing composites have a conductivity about 2 orders of magnitude higher than in the case of the composites prepared without DBSA when PPy loading was lower than 15 wt%. Above this PPy loading the difference in conductivity almost diminished due to a increased amount of PPy polymerized on the surface of the SiC substrate. SiC‐DBSA/PPy composites containing 15 wt% PPy prepared using a molar ratio pyrrole/DBSA = 5, exhibited a very hydrophobic behavior compared to the corresponding DBSA‐free composites, as they floated on water and did not sediment even after a prolonged period of time. POLYM. ENG. SCI., 47:1198–1206, 2007. © 2007 Society of Plastics Engineers