| Abstract: | A new tetrafunctional initiator, di(hydroxyethyl)‐2,9‐dibromosebacate (DHEDBS) HOCH2CH2OOCCHBr(CH2)6CHBrCOOCH2CH2OH], was synthesized and used in preparation of A2B2 miktoarm star copolymers, (polystyrene)2/ poly(1,3‐dioxepane)]2 S‐(PSt)2(PDOP)2], by transformation of atom transfer radical polymerization (ATRP) to cationic ring‐opening polymerization (CROP). First, two‐armed PSt with two primary hydroxyl groups sited at the center of macromolecule (PStBr)2(OH)2] was obtained by ATRP of St with the initiation system of DHEDBS/CuBr/bpy, and used as a chain‐transfer agent in the CROP of DOP with triflic acid as the initiator. Therefore, A2B2 miktoarm star copolymer S‐(PSt)2(PDOP)2 was formed. Its structure was confirmed by the 1H NMR spectrum. Gel permeation chromatography (GPC) curves show that the polymers obtained have a relatively narrow molecular weight distribution. The hydrolysis product of S‐(PSt)2(PDOP)2 was also characterized by 1H NMR and GPC. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 437–445, 2001 |
