Synthesis and characterization of H-shaped copolymers by combination of RAFT polymerization and CROP

A novel trithiocarbonate, S,S′-bis(1-(((5-ethyl-2,2-dimethyl-1,3-dioxane-5-yl)methoxy)carbonyl)propyl) trithiocarbonate (CTA-H), was synthesized in the presence of the anion-exchange resin with OH− form. And then it was used as the chain transfer agent in RAFT polymerizations of styrene (St), the polymers with controllable molecular weights and narrow molecular weight distributions were synthesized. After the terminal acetonide groups was deprotected in the presence of a cation-exchange resin with H+ form, the polystyrene (PSt) with two hydroxyl groups in both chain ends was easily afforded. Then it was used as macro initiator in the cation ring open polymerization (CROP) of 1,3-dioxepane (DOP), and the well-defined H-shaped block copolymers, (PDOP)2PSt(PDOP)2, were successfully prepared. The H-shaped structure was characterized by its IR, GPC and 1H NMR spectra, and also those of the hydrolysis products.