Donor‐acceptor complexes in copolymerization. XV. Cationic polymerization in the copolymerization of styrene and α‐methylstyrene with acrylonitrile and α‐substituted acrylonitriles in the presence of AlEt1.5Cl1.5

The copolymerization of styrene with α‐chloroacrylonitrile and methacrylonitrile in the presence of ethyl aluminum sesquichloride, in the absence as well as in the presence of a peroxide, yields a mixture of equimolar alternating copolymer and styrene‐rich copolymer. The copolymerization of α‐methylstyrene with acrylonitrile and methacrylonitrile under the same conditions yields a mixture of equimolar alternating copolymer and poly‐α‐methylstyrene. The non‐equimolar polymer is produced by a cationic polymerization initiated by the polymerizing complex and its relative amount decreases in the order α‐chloroacrylonitrile > methacrylonitrile > acrylonitrile. The amount of cationic polymer increases (a) at lower temperatures, (b) at low AlEt1.5Cl1.5 concentration, (c) in the presence of peroxide and (d) at high styrene or α‐methylstyrene content in the monomer feed.