The synthesis and chemical polymerization of a thiophene disubstituted with an alkylic and an w-bromine functionalized oligomethylenic chain is described. The obtained polymer, namely the poly [3-hexyl-4-(6-bromohexyl)thiophene], is completely soluble in common organic solvents and its structural, thermal and chemical-physical properties are compared with those of a 'conventional' bromohexyl 3-substituted polythiophene. The new polymer may be considered as a key-intermediate for the synthesis of multifunctional soluble polythiophenes since its self-plastifying feature may permit the insertion on the polymeric side-chains, by simple post-polymerization functionalization reactions, of sterically demanding or strongly interacting functional groups, without final solubility being compromised. (C)2004 Elsevier Ltd. All rights reserved.