Synthesis of A_3B_3-type polystyrene-poly(methyl methacrylate) miktoarm star polymers via combination of stable free radical and atom transfer radical polymerization routes

摘要

An A_3B_3-type miktoarm star polymer was prepared utilizing a "core-out" method via combination of stable free radical polymerization (SFRP) and atom transfer radical polymerization (ATRP).First,SFRP of styrene was carried out by using a miktofunctional initiator,benzene-1,3,5-tricarboxylic acid tris{3-(2-bromo-2-rnethyl-propionyloxy)-2-methyl-2-[2-phenyl-2-(2,2,6,6-tetramethylpiperidin-l-yloxy)ethoxy-carbonyl]propyl) ester,at 125 deg C.Second,previously obtained polystyrene (A_3-type PSt) precursor with three bromine functionalities in the core was used as a macroinitiator for ATRP of methyl methacrylate (MMA) in the presence of Cu(I)Cl and pen-tamethyldiethylenetriamine at 90deg C in order to give an A_3B_3-type miktoarm star polymer,(PSt)_3(-PMMA)_3,with controlled molecular weight and moderate polydispersity (M_w/M_0 < 1.41).The obtained polymers were characterized by gel-permeation chromatography and ~1H-NMR.