Effect of ammonium salts on the radical polymerization of acrylonitrile in liquid sulfur dioxide,,

Abstract

AbstractTetraethyl ammonium bromide, tetramethyl ammonium bromide, ammonium bromide, tetraethyl ammonium chloride, and tetraethyl ammonium iodide were respectively added in the radical polymerization of acrylonitrile in liquid sulfur dioxide. The temperature of polymerization was 50°C. The result showed that the over‐all rate of polymerization was retarded by the addition of these ammonium salts. The retarding effect was caused by the anions and not by the ammonium cations, and the contribution to the retardation by the ammonium salts were in the order of Cl− < Br− ≪ I−, especially in the case of tetraethyl ammonium iodide, the polymerization being completely inhibited. The lowering tendency in the degree of polymerization was also similar in the ammonium salts containing the sam halogenic anion. It was therefore concluded that the retarding effect of ammonium salt was due to the stabilizing action of the halogenic anion on the radical end of growing chains. It was also found that, as it was the case in the radical polymerization of acrylonitrile in liquid sulfur dioxide, no polysulfone but only polyacrylonitrile was obtained. There was no influence of ammonium salt on the course of the polymerization of acrylonitrile in liquid sulfur dioxide.