Synthesis and characterization of a terpolymer of limonene, styrene, and methyl methacrylate via a free-radical route

The free-radical terpolymerization of a monocyclic terpene, namely, limonene (Lim), with styrene (Sty) and methyl methacrylate (MMA) in xylene at 80 ± 0.1°C for 2 h, with benzoyl peroxide (BPO) as an initiator under an inert atmosphere of nitrogen was extensively studied. The kinetic expression was Rpα[BPO]0.5[Sty]1.0[MMA]1.0[Li m]-1.0, where Rp is the rate of polymerization. The overall energy of activation was calculated as 26 kJ/mol. Rp decreased as [Lim] increased. This was due to a penultimate unit effect. The Fourier transform infrared spectra of the terpolymer showed bands at 3025-3082, 1728, and 2851-2984 cm-1 due to C - H stretching of phenyl (-C6H5) protons of Sty, -OCH3 of MMA, and trisubstituted olefinic protons of Lim, respectively. The 1HNMR spectra showed peaks at 7.3-8.1, 3.9-4.4, and 5.0-5.5 δ due to the phenyl, methoxy, and trisubstituted olefinic protons of Sty, MMA and Lim, respectively. The values of the reactivity ratios r1 (MMA; 0.33) and r2 (Sty + Lim; 0.06) were calculated with the Kelen-Tudos method.