Radical copolymerization of acrylonitrile with methyl methacrylate and with α‐methyl styrene in liquid sulfur dioxide

<jats:title>Abstract</jats:title><jats:p>Only polymethyl methacrylate was obtained and polysulfone was not produced when radical polymerization of methyl methacrylate was carried out in liquid sulfur dioxide. When acrylonitrile (AN) with methyl methacrylate (MMA) and with α‐methylstyrene (αMST) were copolymerized respectively, the copolysulfones were not obtained. Liquid sulfur dioxide acted only as a solvent. The following monomer reactivity ratios were obtained: r<jats:sub>1</jats:sub> (AN) = 0.09 ± 0.05, r<jats:sub>2</jats:sub> (MMA) = 1.01 ± 0.07: r<jats:sub>1</jats:sub> (AN) = 0.08 ± 0.03, r<jats:sub>2</jats:sub> (αMST) = 0.25 ± 0.06. Tetraethyl ammonium bromide (TEAB) were added to these copolymerization systems to see that there is almost no change in the values of r<jats:sub>1</jats:sub>'s and r<jats:sub>2</jats:sub>'s. Also no change was observed in the fraction of acrylonitrile and styrene in the copolymer formed with or without added TEAB when the radical copolymerization of AN and styrene in liquid sulfur dioxide was carried out. It was therefore made clear that the effect of TEAB on the radical polymerization of acrylonitrile in liquid sulfur dioxide was acting principally on the termination step.</jats:p>