Novel copolymers of trisubstituted ethylenes with styrene - 7. Methyl 2-cyano-3-dihalophenyl-2-propenoates

Methyl 2-cyano-3-dihalophenyl-2-propenoates, R2C6H3CH=C(CN)CO2CH3 (R-2= 2,4 -difluoro, 2,5-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, and 2-ch loro-6-fluoro), were prepared by the piperidine catalyzed Knoevenagel conde nsation of corresponding disubstituted benzaldehydes and methyl cyanoacetat e. Novel copolymers of the propenoates and styrene were prepared at equimol ar monomer feed by solution copolymerization in the presence of a radical i nitiator. The order of relative reactivity (1/r(1)) was 2,5-difluoro (2.11) > 2,6-difluoro (1.84) > 3,5-difluoro (1.71) > 2,4-difluoro (1.4) > 3,4-dif luoro (0.65) > 2-chloro-6-fluoro (0.59). The copolymers were characterized by IR, H-1 and C-13 NMR, GPC, DSC and TGA. High glass transition temperatur es of the copolymers compared that of polystyrene indicates a substantial d ecrease in chain mobility of the copolymers due to the high dipolar charact er of the trisubstituted ethylene monomer unit.