Novel Copolymers of Styrene. 7. Chlorine Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel trisubstituted ethylenes, chlorine ring-substituted 2-cyano-3-phenyl-2-propenamides, RC₆H₃CH?C(CN)CONH₂ (where R is 2,3-dichloro, 2,4-dichloro, 2,6-dichloro, 3,4-dichloro, 2-chloro-5-nitro, 4-chloro-3-nitro, 5-chloro-2-nitro) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-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- and ¹³C-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 monomers is 2-Cl-5-NO₂ (3.09) > 5-Cl-2-NO₂ (1.88) > 4-Cl-3-NO₂ (0.97) > 2,6-Cl₂ (0.93) > 3,4-Cl₂ (0.31) > 2,4-Cl₂ (0.30) > 2,3-Cl₂ (0.22). High T_g of 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.