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Novel trisubstituted ethylenes, ring substituted 2-cyano-3-phenyl-2-propenamides, RC6H4CH=C(CN)CONH2(where R is 4-carboxy, 2-cyano, 3-cyano, 4-cyano, 4-dimethylamino, and 4-diethylamino) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide prepared and characterized by CHN elemental analysis, IR,1H‒ and13C‒NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution in the presence of a radical initiation (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR,1H‒ and13C‒NMR, GPC, DSC, and TGA. Thus, the order of relative reactivity (1/r1) and the tendency toward alternation of monomer units in the copolymer for the CPA monomers is 4-(C2H5)2N (0.40) > 4-CO2H (0.39) > 3-CN (0.36) > 4-CN (0.35) > 2-CN (0.34) > 4-(CH3)2N (0.33). HighTgof the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (3.5–5.0 wt%), which then decomposed in the 500–800°C range. [ABSTRACT FROM AUTHOR]