Novel Copolymers of 4-Fluorostyrene. 7. Halogen Ring-Disubstituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, halogen ring-disubstituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₃CH= C(CN)₂ (where R is 2,3-Cl₂, 2,4-Cl₂, 2,6-Cl₂, 3,4-Cl₂, 3,5-Cl₂, 2-Cl-4-F, 2-Cl-6-F, 3-Cl-4-F) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (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. The order of relative reactivity (1/r ₁) for the monomers is 2-Cl-4-F (2.42) > 3,4-Cl₂(2.40) > 2,4-Cl₂(1.97) > 2-Cl-6-F (1.86) > 3-Cl-4-F (1.68) > 2,3-Cl₂ (0.89) > 3,5-Cl₂ (0.70) > 2,6-Cl₂ (0.47). High T_g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Softening of the copolymers started in 194–216°C range. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 290–400°C range with residue, which then decomposed in 400–800°C range.