Synthesis of Block Graft Copolymer with Syndiospecific Living Polymerization of Styrene Derivatives by (Trimethyl)pentamethylcyclopentadienyltitanium/Tris(pentafluorophenyl)borane/Trioctylaluminium Catalytic System

Abstract

Two kinds of syndiotactic AB type block copolymers were prepared, which were (1) poly(4-methylstyrene)-block-polystyrene {Poly(4MS-b-S), (A: poly(4MS), B: polystyrene (S))}, (2) poly(4-methylstyrene)-block-poly(styrene-co-3-methylstyrene) {poly[4MS-b-(S-co-3MS)] (A: poly(4MS), B: styrene/3-methylstyrene (3MS) copolymer)}. For the syntheses of these diblock copolymers, the living polymerization catalytic system composed of (trimethyl)pentamethylcyclopentadienyltitanium (Cp*TiMe3) premixed with trioctylaluminium (AlOct3), and tris(pentafluorophenyl)borane (B(C6F5)3) was used at –25°C. Chlorination of the methyl groups of poly[4MS-b-(S-co-3MS)] was conducted by aqueous sodium hypochlorite (NaOCl) and phase-transfer catalyst such as tetrabutylammonium hydrogensulfate (TBAHS). The novel tapered densely grafted diblock copolymer was synthesized with by coupling reaction of living poly(2-vinyl pyridine)lithium (Poly(2VP)Li) with the partly chloromethylated poly[4MS-b-(S-co-3MS)].