Polymer Bulletin, Vol.78, No.1, 493-511, 2021
Determination of monomer reactivity ratios and thermal properties of poly(GMA-co-MMA) copolymers
In this study, the free radical copolymerization of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) was investigated for the first time by solution free radical copolymerization in toluene at 80 degrees C using azobisisobutyronitrile as an initiator. The H-1-NMR spectroscopy has been used for determining the copolymer composition. Monomer reactivity ratios (r values) were calculated by various linear least-square methods. According to the results, using the Kelen-Tudos (KT) and extended Kelen-Tudos (Ex KT) methods the r values were obtained as rG=1.528 +/- 0.168, and rG=1.577 +/- 0.186, respectively. The calculated monomer reactivity ratios showed the higher reactivity for GMA (r(G)) compared to MMA (r(M)). Furthermore, the findings demonstrated random or ideal behavior (rG center dot rM similar or equal to 1) for these copolymers. The monomers sequence distribution as probability of finding the multiple sequence distribution of the GMA and MMA units in copolymers was calculated and showed higher probabilities for GMA sequences. Thermogravimetric analysis of the copolymers had three degradation stages, and the main degradation occurred at third stage (340-456 degrees C) with 56% weight loss. Also, with regard to initial temperature of degradation and T-50, the thermal stability was improved 62% and 2.3%, respectively, by increasing MMA content in copolymer. These studies could uncover the underlying GMA-MMA composition in copolymer, shedding light on the future design of top-performing applications such as UV printing ink and resin industry.
Keywords:Monomer reactivity ratios;Glycidyl methacrylate;Methyl methacrylate;Ideal copolymer;Thermal properties