Block and star block copolymers by mechanism transformation. Part V. Syntheses of polystyrene/polytetrahydrofuran A2B2 miktoarm star copolymers by transformation of CROP into ATRP

Polystyrene (PSt)/polytetrahydrofuran (PTHF) A2B2 miktoarm star copolymers were prepared by transformation of cationic ring-opening polymerization (CROP) to atom transfer radical polymerization (ATRP). The synthetic approach involves the synthesis of PTHF with two secondary bromine groups in the center of a macromolecular chain, (PTHF)2Br2, by the CROP of THF with the symmetric tetrafunctional initiator α,ω-dibromosebasionyl dichloride [ClCOCHBr(CH2)6CHBrCOCl] in conjunction with silver perchlorate; (PTHF)2Br2 was used to initiate the polymerization of styrene to form (PSt)2(PTHF)2 star copolymer. The copolymer obtained was characterized by gel permeation chromatography and 1H NMR spectrum. The hydrolysis of (PTHF)2Br2 was also investigated.