Preparation of amphiphilic block copolymers by Reversible Addition Fragmentation Chain Transfer polymerization

Abstract

Polystyrene macromolecular chain transfer agent (PS-CTA) was firstly synthesized by RAFT of styrene (St) in THF using benzyl dithiobenzoate (BDTB) as chain transfer agent and azobisisobutyronitrile (AIBN) as initiator. It was found that the molar ratio of monomers to chain transfer agents and reaction time had obvious effects on the molecular weight of PS-CTA, and the distribution of molecular weight (M w/M n ) decreases with the increase of the ratio of chain transfer agent to initiator by using gel permeation chromatography (GPC). The amphiphilic block copolymers polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized using PS-CTA by RAFT. The structure, glass transition temperature (Tg) and molecular weight of the diblock copolymer were characterized by nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the structure of PS-b-P4VP was the target product. The segment ratio of PS-b-P4VP could be effectively controlled by changing the polymerization conditions in a large range.