Facile synthesis of A(2m)B(2n)-type starlike copolymers with two types of V-shaped arms by combination of RAFT, ATRP and ROP processes

摘要

Controlled synthesis of A(2m)B(2n)-type (m approximate to n approximate to 8) starlike copolymers comprising an oligomeric poly(-styrene-co-maleimide) core and two types of V-shaped arms individually generated by ATRP and ROP was described. Multistep syntheses involving RAFT copolymerization, end group removal, ATRP of vinyl monomers such as styrene (St), methoxyethyl methacrylate (MEMA) and tert-butyl acrylate (tBA), and ROP of epsilon-caprolactone (CL) were used to construct the target miktoarm stars with controlled molecular weight and relatively low polydispersity (PDI = 1.07-1.22). The resultant star copolymers had high bromide functionality and uniform chain length of ATRP-generated arms, evident from chain extension polymerization and cleavage of arms. Meanwhile, a pH-responsive (PAA)(2m),(PCL)(2n) star was also obtained by selective hydrolysis. The synthetic strategy via combination of RAFT copolymerization and "core first" approach is versatile in constructing various A(2m)B(2n) stars, and this study further paves way for facile synthesis and properties of new types of milctoarm stars. (C) 2015 Elsevier Ltd. All rights reserved.