Structural characteristics of chemical vapor polymerized polypyrrole/polycaprolactam fiber composites

Structural characteristics of polypyrrole (PPy)-coated polycaprolactam (PA6) fiber composites prepared by chemical vapor deposition, in the presence of ferric chloride as the oxidizing agent, were investigated. A multi-layered coating structure was observed by transmission electron microscopy (TEM), where a compact and denser layer existed between the PPy and PA6 fibers with two diffused layers on each side of the denser layer. The compact layer had a thickness of 200-300 nm. The experimental results show that there was no chemical interaction between PPy and PA6 in the PPy-coated PA6 fibers. However, there was a stronger interaction between PPy and PA6 molecules in the interphase of PPy-coated PA6 fiber after heat treatment at elevated temperature. The surface morphology of PPy-coated PA6 fibers changed with the application of different processing treatments, e.g. swelling and heat treatment.