Radical copolymerisation of vinylidene chloride and methacrylonitrile, 2. Sequence microstructure measured by 13C NMR

The radical copolymerisation of vinylidene chloride and methacrylonitrile (M) was studied in bulk, in cyclohexanone, in DMF, and in hexane. From 13C NMR spectra of the copolymers, the dyad and triad monomer sequences and some tetrad and pentad sequences were obtained. Copolymerisation in homogeneous solution showed no dependence on the solvent used (DMF and cyclohexanone). The heterogeneous bulk copolymerisation kinetics were very similar to those of copolymerisation in homogeneous solution, but significantly different from heterogeneous copolymerisation in hexane. The triad sequence distributions could be shown to fit a kinetic scheme incorporating penultimate effects on radical reactivities for copolymerisation from vinylidene chloride rich feeds. However, for copolymerisations from methacrylonitrile rich feeds this model fails because of a dependence upon monomer feed of the reactivity ratio for the ∼︁MM· radical; this might possibly be explained by the involvement of a monomer‐monomer charge‐transfer complex in the copolymerisation.