Novel Copolymers of Styrene. 2. Oxy Ring-Substituted Butyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylenes, oxy ring-substituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO₂C₄H₉ (where R is 2-methoxy, 3-methoxy, 4-methoxy, 2-ethoxy, 3-ethoxy, 4-ethoxy, 4-propoxy, 4-butoxy, 4-hexyloxy, 3-phenoxy) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of oxy ring-substituted benzaldehydes and butyl cyanoacetate and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR, GPC, DSC, and TGA. The order of relative reactivity (1/r₁) for the monomers is 4-methoxy (6.56) > 3-methoxy (2.97) > 2-methoxy (2.72) > 4-butoxy (2.20) > 3-ethoxy (2.18) > 4-propoxy (2.15) > 4-hexyloxy (1.78) > 4-ethoxy (1.66) > 2-ethoxy (1.48) > 3-phenoxy (1.29). Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500°C range with residue (0.8–3.6% wt.), which then decomposed in the 500–800°C range.