Controlled synthesis of low-polydisperse regioregular poly(3-hexylthiophene) and related materials by zincate-complex metathesis polymerization

The recent progress in the development of zincate-complex metathesis polymerization (ZCMP) is reviewed. The Zn-I exchange reaction between 2-bromo-3-hexyl-5-iodothiophene and dilithium tetra-tbutyl zincate ((Bu4ZnLi2)-Bu-t) and subsequent polymerization initiated with a Ni catalyst afforded poly(3-hexylthiophene) s (P3HTs) with predictable molecular weights and low polydispersity indices (PDIs). The direct synthesis of poly(3-(6-hydroxyhexyl) thiophene) was successfully demonstrated without protection of the hydroxyl group. The ligands of the Ni catalyst were further tuned for the preparation of extremely low-polydisperse P3HTs with high reproducibility. Then, the bulkiness and/or the electron-donating effect of the ligands were found to be very important for accessing a living system for ZCMP. Consequently, the modified ZCMP system with the Ni(dcpe) Cl2 catalyst accomplished the preparation of well-defined P3HTs (M-n up to 33 000 g mol(-1)) with extremely low PDIs (1.03-1.11). In addition, an all-conjugated block copolythiophene, P3HT-b-poly(3-octadecylthiophene)(P3ODT), was synthesized for the first time through the sequential monomer addition approach with ZCMP.