Effect of alkyl methacrylate/glycidyl methacrylate copolymer backbone structure on mechanical properties of hydroxyurethane-crosslinked networks

Abstract

The effect of cyclic carbonate functionalized polymer backbones on mechanical and rheological properties of hybrid thermoset resins with hydroxyurethane linkages via vegetable-oil derived diamine were investigated. Atom transfer radical polymerization (ATRP) of binary methyl, ethyl, butyl methacrylate (MMA, EMA, BMA) mixtures with glycidyl methacrylate (GMA) with various GMA initial molar fractions (fGMA = 0.1–0.9) were performed at 70 °C to create precursor backbones with modulated glass transition temperature (Tg). The copolymer compositions were essentially statistical as demonstrated by estimated reactivity ratios. MMA/GMA reactivity ratios were rMMA = 0.80 ± 0.09 and rGMA = 1.35 ± 0.09, which agreed with earlier studies while previously unreported EMA/GMA reactivity ratios were rGMA = 1.10 ± 0.09 and rEMA = 0.31 ± 0.09 and BMA/GMA reactivity ratios were rBMA = 0.67 ± 0.09 and rGMA = 1.45 ± 0.09. The synthesized copolymers were then carbonated, converting the pendent epoxy functional groups to cyclic carbonates. The carbonated copolymers were reacted with the vegetable oil-derived diamine Priamine 1074 to form relatively rigid side chains via hydroxyurethane linkages to the backbone. Degree of flexibility of backbones and cyclic carbonate functionality were manipulated to synthesize crosslinked networks with Young's moduli ranging from 395 MPa to 1250 MPa.