Copolymers of N-cyclohexylacrylamide and n-butyl acrylate: synthesis, characterization, monomer reactivity ratios and mean sequence length

Copolymerization of N-cyclohexylacrylamide (NCHA) and n-butyl acrylate (BA) was carried out in dimethylformamide at 55 +/- 1 degrees C using azobisisobutyronitrile as a free radical initiator. The copolymers were characterized by (1)H-NMR spectroscopy and the copolymer compositions were determined by (1)H-NMR analysis. The reactivity ratios of the monomers were determined by both linear and non-linear methods. The reactivity ratios of monomers determined using linear methods like Fineman-Ross (r(1) = 0.37 and r(2) = 1.77), Kelen-Tudos (r(1) = 0.38 and r(2) = 1.77), ext. Kelen-Tudos (r(1) = 0.37 and r(2) = 1.75) Yezrieler-Brokhina-Roskin (r(1) = 0.37 and r(2) = 1.77) and non-linear methods like Tidwell-Mortimer (r(1) = 0.37 and r(2) = 1.76), ProCop (r(1) = 0.36 and r(2) = 1.82). The Q and e values for NCHA are 0.67 and 0.68 respectively. Mean sequence lengths of copolymers are estimated from r(1) and r(2) values. It shows that the BA units increases in a linear fashion in the polymer chain as the concentration of BA increases in the monomer feed.