ACRYLONITRILE ACRYLIC ACIDS COPOLYMERS .1. SYNTHESIS AND CHARACTERIZATION

Acrylonitrile (AN) was copolymerized with acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA) by the aqueous suspension method at 40-degrees-C with ammonium persulfate and sodium metabisulfite as the redox initiator. The reactivity ratios for the AN-AA and AN-IA systems were also calculated by the Finemann-Ross and the Kelen-Tudos methods. Higher r2 (AA) for the AN-AA system in comparison to r2 (IA) for the AN-IA system indicates greater reactivity of AA toward the propagating species. The influence of comonomers on intrinsic viscosity, tacticity, and number-average sequence lengths was studied. C-13-NMR spectra revealed that AN copolymers having approximately 2 mol % of AA have a greater percentage (> 30%) of isotactic content than of homopolyacrylonitrile. Tacticity has also been calculated from infrared spectra of the polymers using stereospecific absorption bands at 1250 and 1230 cm-1. (C) 1993 John Wiley & Sons, Inc.