Effects of CoCl2 and Other Additives on the Oxidative Chemical Synthesis and Properties of Poly(3-hexylthiophene)

Abstract

The chemical oxidative polymerisation of 3-hexylthiophene (3HT) by FeCl3 and the effects of reaction modifiers on the properties of the resulting polymer (P3HT) have been investigated. The process of polymerisation was identified using inhibitors that each affected one possible reaction mechanism. Gel permeation chromatography (GPC), UV-visible spectroscopy and proton nmr spectroscopy were employed to investigate the effects of the organic inhibitors and of added cobalt (II) chloride. Polymerisation appeared to proceed by two different mechanisms, one of which was strongly inhibited by cobalt chloride, whilst the other was favoured. CoCl2 was found to increase the molecular weight of the polymer substantially, and to make it more regioregular. As a result, the electronic conductivity of lightly iodine-doped P3HT was also enhanced.