Synthesis of a Novel Graft Copolymer with Hyperbranched Poly(glycerol) as Core and Y-Shaped Polystyrene-b-Poly(ethylene oxide)2 as Side Chains

The graft copolymers composed of Y shaped polystyrene b-poly(ethylene oxide)(2) (PS b-PEO2) as side chains and hyperbranched poly(glycerol) (HPG) as core were synthe sized by a combination of click chemistry and atom transfer radical polymerization (ATRP) via graft from and graft onto strategies Firstly macromitiators HPG Br were obtained by esterification of hydroxyl groups on HPG with bromoisobutyryl bromide and then by graft from strategy graft copolymers HPG g (PS Br) were synthesized by ATRP of St and further HPG g (PS N-3) were prepared by azidation with NaN3 Then the precursors (Bz PEO)(2) alkyne with a single alkyne group at the Junction point and an inert benzyl group at each end was synthesized by sequentially ring opening polymerization (ROP) of EO using 3 [(1 ethoxyethyl) ethoxyethyl] 1 2 propanediol (EEPD) and diphenylmethylpotassium (DPMK) as coinitiator termination of living polymeric species by benzyl bromide recovery of protected hydroxyl groups by HCI and modification by propargyl bromide Finally the click chemistry was conducted between HPG g (PS N3) and (Bz PEO)2 alkyne in the presence of N ' N ' N ' N ' N ' pentamethyl diethylenetnamme (PMDETA)/CuBr system by graft onto strategy and the graft copolymers were characterized by SEC H-1 NMR and FTIR in details (c) 2010 Wiley Periodicals Inc J Polym Sci Part A Polym Chem 48 5856-5864 2010