Chapter 4: Controlled Synthesis of Chain End Functional, Block and Branched Polymers Containing Polythiophene Segments

The controlled synthesis of regio-regular poly(3-alkylthiophene) is an important topic in the synthetic chemistry of polymers and in optoelectronics because the well-defined poly(3-alkylthiophene) segments can be used as building blocks in many architectural polymers, including chain-end-functional, block, graft, star and hyperbranched polymers. These polymers have unique optical and electronic properties that are different from those of pristine homopolymers. By exploiting their semiconductivity and specific polymer architectures, possible applications of these polymers include batteries, capacitors, light-emitting diodes, transistors and photovoltaic devices. A large number of architectural polymers containing poly(3-alkylthiophene) segments have been synthesized by combining ‘living’/controlled polymerization techniques, including anionic, cationic, radical and, recently, condensation chain-growth polymerization. This chapter reviews recent progresses in the synthesis of regio-regular poly(3-alkylthiophene), well-defined chain-end-functional poly(3-alkylthiophene)s and block and branched copolymers consisting of poly(3-alkylthiophene) segments, focusing on the synthetic methodologies used to control their regio-regularity, molecular weight, dispersity, branching and composition.