CRYSTALLINE-STRUCTURE DETERMINATION FOR POLY(4,4-DIALKYL-2,2-BITHIOPHENES)

The crystalline structure of poly(4,4'-dialkyl-2,2'-bithiophenes) (PDA BTs), the regioregular pure 'head to head, tail to tail' coupled analo gues of poly( 3-alkylthiophenes) (P3ATs) has been determined by use of X-ray diffraction and computer modelling. Three types of samples have been considered, namely, those containing n-hexyl, n-octyl and n-decy l groups. The main conclusion of this work is that the crystalline str ucture of PDABTs can be explained by the orthorhombic unit cell, but t he polymer chains are twisted to a higher degree than in the case of P 3ATs. The influence of stretching and doping processes on the structur al properties of PDABTs has also been investigated.