X-RAY-DIFFRACTION AND INFRARED-SPECTROSCOPY STUDIES OF ORIENTED POLY(3-ALKYLTHIOPHENES)

Poly(3-octylthiophene) was stretched at 100-degrees-C to a final length up to five times the initial length. The degree of orientation in the crystalline and amorphous phases has been determined by means of X-ray diffraction and polarized infra-red spectroscopy. The value of the orientation function in the crystalline region was 0.72, which is comparable to the value 0.81 predicted from a theoretical calculation based on the draw ratio. The orientation of the amorphous phase was considerably lower, 0.47. Based on X-ray diffraction data from poly(3-alkytiophenes) with different lengths of the side-chain, a tentative crystal structure for the poly(3-alkylthiophenes) is proposed.