NUCLEAR MAGNETIC RESONANCE STUDIES ON MICROSTRUCTURE OF ETHYLENE COPOLYMERS .I. SEQUENCE DISTRIBUTION IN ETHYLENE-VINYL FORMATE COPOLYMERS

The 220-MHz proton nmr spectra of ethylene-vinyl formate (E-VF) copolymers dissolved in several solvents have been obtained. In deuteriochloroform solution, the resonances of formate protons in the comonomer triads of VF-VF-VF, VF-VF-E(E-VF-VF), and E-VF-E can be readily resolved. Moreover, spin-decoupling experiments on the methine protons and peak intensity measurements of the methylene protons indicate that the interpretations of nmr spectra of E-VF copolymers are unambiguous. It was found that the monomers in these copolymers are distributed in a blockier fashion than the statistically random (Bernoullian) comonomer sequence distribution.