A simple method to fabricate poly(aniline-co-pyrrole) with highly improved electrical conductivity via pre-polymerization

Abstract

A highly conductive aniline and pyrrole copolymer (P(An-Py)) was fabricated by properly controlling pre-polymerization time. The electrical conductivity of P(An-Py) by proper pre-polymerization achieved the same order of magnitude (10⁻¹ S cm⁻¹) with their homopolymers, or even slightly higher, which was irrelated to the molar ratio of two monomers. Only by 15 min pre-polymerization, the electrical conductivity of P(1An-3Py) and P(1An-1Py) improved more than 3 orders of magnitude and 4 times, respectively. Electron microscopic analysis showed there was no obvious change in the morphology of the copolymers with pre-polymerization. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that the copolymers backbone contained many small aniline chains after pre-polymerization. The number of quasi-hydrogen bonding between N of pyrrole and adjacent free H⁺ of protonated aniline was greatly reduced. As a result, the number of free H⁺ of protonated aniline chain in copolymer was significantly increased, thus the carrier concentration and electrical conductivity increased sharply. Our results suggested that properly controlling the pre-polymerization time before copolymerization was a simple but effective way to highly improve the conductivity of copolymers that aniline and other monomer copolymerized.