Reverse iodine transfer copolymerization of styrene and acrylonitrile: copolymer synthesis, characterization and kinetic study

Random copolymers of poly (styrene-co-acrylonitrile) (SAN) via reverse iodine transfer copolymerization of styrene (St) and acrylonitrile (AN) were synthesized using carboxyl functional initiator 4, 4'-azobis (4-cyanovaleric acid) (ACVA) and molecular iodine (I-2) at 80 degrees C. The characterization of resultant random copolymer via FT-IR, H-1-NMR, GPC, and DSC analysis confirmed that well-defined SAN copolymers with different copolymer compositions of acrylonitrile (F-AN = 0.23 -0.46) and monocarboxylic acid functionality, were synthesized. The kinetics results showed that the copolymerization rate obeyed the first-order kinetics model with respect to the monomer concentration, a linear increase of the molecular weight with increasing monomer conversion and a relatively low dispersity index (D similar to 1.4) was observed. The reactivity ratios of the St and AN were calculated using the extended Kelen-Tudos (K-T) method to be r(st) = 0.431 +/- 0.0406 and r(AN) = 0.224 +/- 0.0164, respectively. Finally, the Barton model generated a satisfactory fit to the experimental data of the copolymers' glass transition temperatures.

Automated summary

Random copolymers of poly (styrene-co-acrylonitrile) with different compositions of acrylonitrile and monocarboxylic acid functionality were successfully synthesized through reverse iodine transfer copolymerization. The kinetics results, reactivity ratios, and glass transition temperatures of the copolymers were analyzed and showed promising characteristics for potential applications.