A theoretical study of structural defects in conjugated polymers

Abstract

Accurate ab-initio calculations are performed for pyrrole and thiophene oligomers bonded through alpha and beta carbons. The thermodynamical stabilitiy of all possible binding types including the branched forms of tetramers and pentamers are compared. Employing the probabilities obtained from these calculations, a Monte Carlo type growth scheme is applied to predict branching as functions of the chain length and temperature. A high degree of branching for polypyrrole is reported whereas the linear chains dominate the structure of polythiophene.