NMR study of poly(vinyl chloride)‐β,β‐<i>d</i>₂

Abstract

Abstract The high‐resolution NMR spectra at 60 and 100 Mcps of poly(vinyl chloride)‐β,β‐ d 2 in o ‐dichlorobenzene, pyridine, and C 2 HCl 5 solutions are reported. The use of low molecular weight samples and of { D } spin‐decoupling experiments, which yield higher resolution spectra, results in the observation of a number of additional resonances for the α‐proton. These can be interpreted in terms of pentad configurational sequences of monomer units. It is found that, whereas the S syndiotactic pentads cannot be resolved, two components of the H heterotactic and all of the possible I isotactic pentads are clearly discernible. From the tacticity values of polymers prepared at +40, 0, and −40°C, enthalpy and entropy of activation for isotactic and syndiotactic monomer placement are found to be 630 cal/mole and 1.5 eu, respectively.