Synthesis and Characterization of Copolymers of Acrylonitrile with Isobornyl Acrylate and Methacrylate

Abstract

Free radical copolymerization of acrylonitrile with isobornylacrylate (IBA) and isobornyl methacrylate (IBM) has been investigated in N,N-dimethyl formamide at 60 ± 1ºC using 2,2- azobisiso- butyronitrile (AIBN) as an initiator by ¹H NMR analysis. The monomer reactivity ratios were computed by both Fineman-Ross (F-R) and Kelen-Tudos (K-T) methods. The reactivity of acrylate was found to be more than that of methacrylate towards acrylonitrile. The reactivity ratio values suggest the formation of random copolymers which has been supported by the azeotropic composition evaluation. The mean sequence length (n) and probabilities (p) in the formation of various structural units were evaluated. The molecular weights of the polymers were determined by gel permeation chromatography. The molecular weights of the copolymers increase with the increase of the acrylonitrile content. The solubility parameters were determined with viscometric method. The solubility parameter values of acrylate copolymer are more than the corresponding methacrylate copolymer. The glass transition temperatures of the copolymers were determined by differential scanning calorimetry. Thermogravimetric analysis of the copolymers was performed and their thermal stabilities were studied. The T_g values of acrylate copolymers are less than the corresponding methacrylate copolymers. Thermal stability of IBM copolymers is found to be more than that of IBA copolymers. The dielectric properties of the copolymers were also studied. The dielectric loss of the copolymers is found to be shifting to a higher temperature from acrylate to methacrylate copolymers.