Polymers Based on Methacrylate Bearing Coumarin Side Group: Synthesis via Free Radical Polymerization, Monomer Reactivity Ratios, Dielectric Behavior, and Thermal Stabilities

Copolymerization and homopolymerization of 7-methacryloyloxy coumarin (MAOC) and its copolymers with benzyl methacrylate (BMA), methyl methacrylate (MMA), ethyl methacrylate (EMA), and isobuthyl methacrylate (IBMA) were performed by the free radical polymerization method (FRP) at low conversions (<15%). The resulting polymers were characterized by FTIR, 1H NMR, GPC, DSC, and TGA. The monomer reactivity ratios of MAOC and BMA were computed using Kelen-Tüdös (K-T) and Fineman-Ross (F-R) methods and were found to be r1=0.45, r2=1.29; r1=0.46; r2=1.33, respectively (r1 is monomer reactivity ratio of MAOC). Blends of poly(MAOC) and poly(BMA) obtained via FRP method were prepared by casting films from dichloromethane solution and were characterized by DTA and TGA techniques. Dielectric measurements for MAOC homopolymer and its copolymers with EMA, MMA, and IBMA were carried out by means of an impedance analyzer as a function of temperature and frequence. Dielectric properties of polymer samples prepared in a plate form were measured at room temperature over the frequency range 0.1 kHz–2 MHz and given as compared with each other.