Synthesis of A3B3-type polystyrene–poly(methyl methacrylate) miktoarm star polymers via combination of stable free radical and atom transfer radical polymerization routes

Abstract

An A3B3-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-methyl-propionyloxy)-2-methyl-2-[2-phenyl-2-(2,2,6,6-tetramethylpiperidin-1-yloxy)ethoxy-carbonyl]propyl} ester, at 125°C. Second, previously obtained polystyrene (A3-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 pentamethyldiethylenetriamine at 90°C in order to give an A3B3-type miktoarm star polymer, (PSt)3(-PMMA)3, with controlled molecular weight and moderate polydispersity (M w/M n < 1.41). The obtained polymers were characterized by gel-permeation chromatography and 1H-NMR.