REACTIVITY RATIOS AND SEQUENCE DETERMINATION OF ACRYLONITRILE HEXYL METHACRYLATE COPOLYMERS BY ONE-DIMENSIONAL AND 2-DIMENSIONAL NMR-SPECTROSCOPY

Acrylonitrile/hexyl methacrylate copolymers of different monomer compo sition were prepared by photopolymerization using uranyl ions as photo sensitizer. The copolymer composition data were used to calculate the comonomer reactivity ratios according to the Kelen Tudos (KT) and the error-in-variables model (EVM) method. The reactivity ratios obtained from the EVM method are r(A) = 0.14 +/- 0.03 and r(H) = 1.32 +/- 0.17. The microstructure was obtained in terms of distribution of A and H c entred triad sequences from C-13{H-1} NMR spectra of the copolymers. T he copolymerization mechanism was determined by using Cheng's methodol ogy. It was found that the Markov second order model gave a good fit t o the experimental data. The complex and overlapping proton and carbon signals of A/H copolymers were assigned to various compositional and configurational sequences with the help of inverse HETCOR experiments.