Huanhuan Liu, Xiao Jiang, Rongjian Bian, Min Tong, Dandan Tang, Xiangdong Zhou, Youliang Zhao*, “Facile synthesis of A_2mB_2n-type starlike copolymers with two types of V-shaped arms by combination of RAFT, ATRP and ROP processes”, Polymer, 2015, 64, 249–259 (DOI: 10.1016/j.polymer.2015.01.059).

http://www.sciencedirect.com/science/article/pii/S0032386115001184

Controlled synthesis of A_2mB_2n-type (m ≈ n ≈ 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 ε-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_2mB_2n stars, and this study further paves way for facile synthesis and properties of new types of miktoarm stars.