Synthesis and characterization of soluble polypyrrole–poly(ɛ-caprolactone) polymer blends with improved electrical conductivities

Polypyrrole–poly(ɛ-caprolactone) (PPy–PCL) blends were prepared through an in situ deposition technique wherein different amounts of poly(ɛ-caprolactone) were added during the polymerization of pyrrole. Ammonium persulfate was used as an oxidant in the polymerization of polypyrrole (PPy). Compared with pure PPy, the blends showed higher solubility in many organic solvents. The composition and structural characteristics of PPy–PCL were determined by Fourier transform infrared, ultraviolet–visible, and X-ray photoelectron spectroscopic methods. Scanning electron and transmission electron microscopic methods were performed to observe the morphology of the PPy–PCL blends. The temperature-dependent conductivity of the PPy–PCL blends was measured at 300–500 K. The conductivity increased with increasing PCL concentration in the blends, which can be explained by the increased mobility of charge carriers at high PCL concentrations. Based on the temperature dependence of the electrical conductivity, hopping may be the conduction mechanism involved in the PPy–PCL blending process.