Synthesis of epoxy functionalized four-armed star diblock copolymers by atom transfer radical polymerization

Well-defined epoxy functionalized four-armed star diblock copolymers were synthesized by atom transfer radical polymerization (ATRP) using the “core-first” approach. In accordance with this synthetic methodology, in a first step, bromine-terminated four-armed star homopolymers of styrene (S) and methyl methacrylate (MMA) were prepared. Then, in a second step, the S[PS-Br]4 and S[PMMA-Br]4 samples were employed as macroinitiators in the ATRP of an oxirane functionalized monomer, like glycidyl methacrylate (GMA). These copolymerization reactions were carried out in benzonitrile solution, at relative-low polymerization temperature, 50 °C, and using copper chloride with N,N,N′,Nʺ,Nʺ-pentamethyldiethylenetriamine (PMDETA) as the catalyst system. Linear first-order kinetics with respect to the [GMA]0 were observed, and the analyses of the copolymers obtained by means of size exclusion chromatography (SEC) and 1H nuclear magnetic resonance spectroscopy (1H NMR) demonstrated the high degree of control achieved in the copolymerizations. Moreover, their crosslinkable capacity was studied with a linear diamine by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), indicating their clear potential for epoxy resins technologies.