Synthesis of asymmetric star‐branched block copolymers based on PS, PTHF, and PMMA by combination of cationic ring opening polymerization and redox polymerization methods

Abstract

AbstractAsymmetric star‐branched block copolymers based on polystyrene (PS), polytetrahydrofuran (PTHF), and poly(methyl methacrylate) (PMMA) were synthesized by a combination of cationic ring opening polymerization and redox polymerization methods in two steps. At first, cationic ring opening polymerization of THF was initiated by using chain‐end‐multifunctionalized polystyrenes with 2, 4, and 8 benzyl bromide moieties as initiators in the presence of AgSbF6 at 30°C to obtain 3‐, 5‐, and 9‐arm AB2, AB4, and AB8 type asymmetric star‐branched polymers consisting of PS (A) and PTHF‐OH (B) segments. Polymers obtained in this way were characterized by gel permeation chromatography, FTIR, 1H NMR, and thermal analysis (DSC and TGA). At second step, redox polymerization of methyl methacrylate was initiated by using these characterized asymmetric star‐branched polymers as macroinitiators in the presence of Ce(IV) salt at 40°C to obtain PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers. PS‐s‐(PTHF‐b‐PMMA)n (n = 2, 4, and 8) asymmetric star‐branched block copolymers obtained were purified by fractional precipitation method before characterization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 516–522, 2006