Spectroscopic comparison between poly[3-(6-methoxyhexyl)thiophene]s with different steric hindrance

An alternating methoxyhexylthiophene–thiophene copolymer was synthesized from 3-(6-methoxyhexyl)-2,2′-bithiophene and studied chiefly by means of optical absorption and nuclear magnetic resonance spectroscopy. The results were compared with those of the previously obtained poly[3-(6-methoxyhexyl)-2,5-thienylene]. The differences in the UV-Vis spectra of the two polymers in pure solvents, solvent/non-solvent mixtures and in films are discussed on the basis of the microstructure and the steric hindrance along the backbone. NMR spectroscopy revealed copolymer configuration to be regiorandom with a slight prevalence of head-to-head and tail-to-tail junctions.