Synthesis and characterization of all-conjugated diblock copolymers consisting of thiophenes with a hydrophobic alkyl and a hydrophilic alkoxy side chain

Novel thiophene-based all-conjugated block copolymers consisting of 3-hexylthiophene and 3-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}thiophene were synthesized using the Grignard metathesis (GRIM) polymerization method in the presence of Ni(dppp)Cl₂. Favorable transfer of the catalytic site from an electron-poor precursor to an electron-rich monomer was found to produce the block copolymer. The molecular weights of the copolymers increased slightly with increasing polymerization temperature (10.1 × 10³ M _n (35 °C) → 11.1 × 10³ M_n (55 °C)), suggesting that transit of the catalytic site was accelerated at high temperatures. Size exclusion chromatography, UV-vis and photoluminescence spectroscopies, and cyclic voltammetry measurements confirmed that the polymers were block copolymers. The blocks were associated and organized relative to one another in adjacent chains.