Synthesis of a donor-acceptor diblock copolymer via two mechanistically distinct, sequential polymerizations using a single catalyst

Treatment of a Ni-terminated poly(3-hexylthiophene) (P3HT), generated in situ from 5-chloromagnesio-2-bromo-3-hexylthiophene and Ni(1,3- bis(diphenylphosphino)propane)Cl₂, with a perylene diimide-functionalized arylisocyanide monomer effects a chain-extension polymerization to afford a donor-acceptor diblock copolymer using a single catalyst and in a single reaction vessel. The two mechanistically distinct polymerizations proceed in a controlled, chain growth fashion, allowing the molecular weight of both the P3HT and poly(isocyanide) blocks to be tuned by adjusting the initial monomer-to-catalyst ratios. The resulting materials are found to self-assemble into crystalline, lamellar stacks of donor and acceptor components in the solid state, and also exhibit fluorescence quenching in thin films, properties which poise these materials for use in organic photovoltaic applications. A donor-acceptor block copolymer composed of mechanistically distinct poly(3-hexylthiophene) (P3HT) and perylene diimide (PDI)-functionalized poly(isocyanide) segments is synthesized in one pot via sequential monomer addition using a single Ni catalyst. The diblock copolymer exhibits a fibrillar nanomorphology and undergoes photoluminescence quenching in the solid state.