Regioregular poly(3-alkylthiophenes) (PATs) represent an import-ant class of polymers that are environmentally stable and display high electrical conductivity. Despite their excellent electrical properties, PATs do not exhibit very good mechanical and processing properties. This issue is addressed here by integrating poly(3-alkylthiophene) in copolymer structures with various polymer blocks that display better mechanical properties, leading to a variety of polymeric materials with desired properties. We describe a new method for the synthesis of poly(3-alkylthiophene) block copolymers using vinyl terminated regioregular poly(3-alkylthiophene) as precursors via atom transfer radical polymerization (ATRP). (c) 2005 Elsevier Ltd. All rights reserved.