Copolymerization of Methyl Methacrylate With 2-Methylbenzyl Methacrylate and 4-Methylbenzyl Methacrylate: Synthesis, Characterization, and Monomer Reactivity Ratios

Two types of copolymers based on 2-methylbenzyl methacrylate and 4-methylbenzyl methacrylate with methyl methacrylate were synthesized. Several copolymers of 2-methylbenzyl methacrylate (2-MBZMA) and 4-methylbenzyl methacrylate (4-MBZMA) with methyl methacrylate (MMA) having different copolymer compositions were performed in 1,4-dioxane using 2,2′-azobisisobutyronitrile (AIBN) as a free radical initiator at 60±1°C. The copolymers were characterized by FT-IR, 1H- and 13C-NMR spectroscopic techniques. The composition of monomeric units in the copolymer system was calculated using 1H-NMR spectroscopy by comparing the integral values of well separated aromatic and aliphatic proton peaks. The reactivity ratios were calculated by employing Fineman-Ross and Kelen-Tüdös methods. The values of r1 and r2 obtained by the Fineman-Ross and Kelen-Tüdös methods appear to be in close agreement with each other, i.e., r1(2-MBZMA):1.03±0.039 and r2(MMA): 0.77±0.012 for the copoly(2-MBZMA-MMA) system, r1(4-MBZMA): 0.97±0.040 and r2(MMA):0.77±0.050 for the copoly(4-MBZMA-MMA) system. Thermal stabilities of the homo- and co-polymers were investigated using thermogravimetric analysis, while differential scanning calorimetry was used to determine the glass transition temperature.