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

Abstract

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-t butyl zincate (t Bu 4 ZnLi 2) 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)Cl 2 catalyst accomplished the preparation of well-defined P3HTs (M n up to 33 000 gmol-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. © 2014 The Society of Polymer Science, Japan (SPSJ).