Facile synthesis of well-defined coil-rod-coil block copolymer composed of regioregular poly(3-hexylthiophene) via anionic coupling reaction

We introduced a facile synthetic strategy of coil-rod-coil triblock copolymers containing regioregular poly(3-hexylthiophene) (P3HT) block via anionic coupling reaction. Two different coil blocks (poly(2-vinylpyridine) (P2VP) and polyisoprene (PI)) were selected. P2VP-b-P3HT-b-P2VP copolymer was synthesized in a polar solvent of tetrahydrofuran, whereas PI-b-P3HT-b-PI copolymer was synthesized in a nonpolar solvent of benzene. For the synthesis of both block copolymers, the chain ends of the P3HT were capped by the aldehyde group. Because of the higher electrophilicity of the carbon in the aldehyde group compared with that in allyl (or vinyl) group, the coupling reaction between living anions in the coil blocks and aldehyde-capped P3HT was carried out more effectively. When the excess amount of the living P2VP (or PI) anions was used, all of aldehyde-capped P3HT were completely reacted with P2VP (or PI) anions without leaving any P3HT homopolymer in the product. When the unreacted P2VP (or PI) was removed by column chromatography, two synthesized triblock copolymers had narrow molecular weight distributions.