Epoxy-based triblock, diblock, gradient and statistical copolymers of glycidyl methacrylate and alkyl methacrylates by nitroxide mediated polymerization

Abstract

A series of triblock, diblock, gradient and statistical copolymers of glycidyl methacrylate (GMA) and C13 methacrylates (C13MA, alkyl methacrylates with the average side-chain length of 13.0) were synthesized by nitroxide mediated polymerization (NMP) using Dispolreg 007 in 50 wt% dioxane at 90 °C. The polymers had the number average molecular weights (Mn) in the range of 23-46 kg mol−1 and dispersities (Đ) of 1.5–1.9. For the GMA/C13MA statistical copolymerization, reactivity ratios rGMA = 1.17 ± 0.09 and rC13MA = 0.65 ± 0.09 were determined. For statistical copolymers with GMA ratio (FGMA) of 0.5–0.8, the appearance of a melting point (Tm) at −43 to −19 °C and two glass transition temperatures (Tg) in the range of −53 to 11 °C indicated the possibility of micro-phase separation and a weak gradient polymerization. TGA showed ash content up to 13 wt% for GMA/C13MA copolymers at 600 °C, suggesting the possibility of high flame retardancy. Furthermore, a transition from elastic solid to viscous liquid behavior was detected by an oscillatory frequency sweep at 30 °C for triblock copolymers of GMA/C13MA (FGMA = 0.6–0.7, crossovers at 100–200 rad s−1) and gradient polymers with high GMA content (FGMA = 0.88, crossover at 10 rad s−1).