Ring-opening copolymerization of epoxy-terminated polystyrene macromer with epichlorohydrin and study on properties of the copolymers

Abstract

The synthesis and ring-opening copolymerization of epoxy-terminated polystyrene (PS-ep) macromer with epichlorohydrin (ECH) as well as some properties of the graft copolymers, were studied. The results showed that content of the epoxy-terminated macromer in the crude macromer can be increased by anionic polymerization of styrene in cyclohexane, and capping with propylene sulfide, followed by termination with ECH at 0 °C. The ring-opening copolymerization of ECH with the macromer can be performed by using a quaternary catalyst system which was composed of triisobutyl aluminium–phosphoric acid–water–amine in the molar ratio of 1:0.25:0.25:0.1–0.15. When the charging weight percentage of PS-ep/ECH=25–65% and M n of PS-ep was 2.6–10×10 3, the conversion of ECH was greater than 95% and the conversion of the macromer or grafting efficiency was 35–65%. The purified copolymer was characterized by IR, 1H NMR and dynamic viscoelastometer to be a copolymer of ECH with polystyrene (PS) grafts. Transmission electron microscope showed the existence of PS domains in the continuous phase of polyepichlorohydrin (PECH). In a certain range of compositions the graft copolymer behaves like a thermoplastic elastomer. The graft copolymer can be melted and processed repeatedly. Its oil and solvent resistance were better than PS and similar to PECH rubber. The graft copolymer can be used as a compatibilizer for blending PECH with PS to form thermoplastic elastomer blends. Only 2% of it based on the blend is needed to raise the tensile strength of the blends obviously.