Thermochromic properties of polythiophenes: structural aspects

摘要: Temperature-dependent optical absorption measurements have revealed important thermochromic effects in poly(3-dodecylthiophene) and poly(3-octyloxy-4-methylthiophene) between 25 150°C which are related to a planar non-planar transition of the main polymer chain. This conformational is caused by an increase repulsive intrachain steric interactions upon heating, then force thiophene backbone adopt conformation. On other hand, as observed with poly(3-octyloxythiophene), if side chains do not lead large interactions, can maintain highly conjugated structure even at high temperatures while, too strong (e.g. poly(3,3′-dihexyl-2,2′-bithiophene)), no co-planar conformation be adopted.