Understanding of the effects of fundamental molecular structure on material characteristics in conducting polymers' requires the construction of materials with very well-defined physical structures. 2 Efforts to prepare regioregular head-to-tail (HT) poly (3-alkylthiophene~)~( PATS) led to the development, in our lab4 and then el~ ewhere,~ of a method for the chemical polymerization of 3-alkylthiophenes that provides essentially 100% HT co~ ...