Trisubstituted ethylenes, phenoxy ring-substituted isopropyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2CH(CH3)2where R is 2-(3-methoxyphenoxy), 2-(4-methoxyphenoxy), 3-(4-methoxyphenoxy), 3-(4-methylphenoxy), 4-(4-bromophenoxy), 4-(4-fluorophenoxy) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of phenoxy ring-substituted benzaldehydes and isopropyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. All the ethylenes were copolymerized with styrene in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 270-500ºC range with residue (2-7% wt.), which then decomposed in the 500-800ºC range.