Cationic reactions depropagation

Yamashita et al. [157] have derived a copolymer composition equation that includes the depropj ation reaction such as might be expected in the cationic copolymerization of BCMO and THF. They consider two models. For the first one it is assumed that monomer M2 adds reversibly to both active chain ends mf and m and that depropagation by detachment of an M1 unit is neglected. The elementary reactions are then... 

In contrast to other poly (olefin sulfone) s, little isomerization of the olefin occurs during cationic depropagation. The degradation of PMPS is extremely rapid and it is possible that the lifetime of the cationic intermediates may be too short for appreciable isomerization to occur. However, isomerization of the 2-methyl-l-pentene product to 2-methyl-2-pentene did occur during the postexposure period. The isomerization proceeded both in solution and in the solid state. It seems unlikely that the reactive intermediates (e.g. cations and free radicals) produced by irradiation catalyse the isomerization reaction since they would be expected to be destroyed during dissolution. However sulfur dioxide is well known to form charge transfer complexes (CTC) with olefins (1) and we propose that the isomerization occurs via such an intermediate ... 

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