Copolymerization of 4‐cyclopentene‐1,3‐dione with acrylonitrile and methyl methacrylate

Abstract

AbstractThe copolymerization of acrylonitrile and methyl methacrylate with 4‐cyclopentene‐1,3‐dione (M2) is reported. The copolymers were prepared by heating the monomer feeds in sealed tubes with α,α′‐azobisisobutyronitrile. Infrared bands for both the β‐diketone and the nitrile, in the case of acrylonitrile, or ester, in the case of methyl methacrylate, indicated that copolymerization had occurred. The acrylonitrile copolymers were insoluble in the common solvents and swelled on treatment with dimethylformamide and dimethylsulfoxide. The methyl methacrylate copolymers were partially soluble in the usual solvents with the solubility and gel content varying with the composition of the copolymers. Solution viscosities indicated high molecular weights. The reduced specific viscosity of the sodium salt of the 0.05 methyl methacrylate copolymer increased with decreasing concentration, a characteristic typical of polyelectrolytes. The compositions of the copolymers were determined from the nitrogen analyses for acrylonitrile copolymers, and the ultraviolet absorption of the β‐diketone for the methyl methacrylate copolymers. The molar extinction coefficient of the β‐diketone structural unit was estimated from a study of model compounds. The reactivity ratios were evaluated by the usual methods. For the acrylonitrile (M1)–4‐cyclopentene‐1,3‐dione (M2) system, r1 = 3.67, r2 = 0.21. For the methyl methacrylate (M1)–4‐cyclopentene‐1,3‐dione (M2) system r1 = 7.4, r2 = 0.083. For each system Q and e values for 4‐cyclopentene‐1,3‐dione were evaluated. The average values are Q = 0.20, e = 1.42. The behavior of 4‐cyclopentene‐1,3‐dione is compared with maleic anhydride and N‐butylmaleimide with respect to the reactivity of the monomer, the reactivity of the radical, and the effective polarity of the double bond.