POLYMER NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY .16. POLY(VINYL CHLORIDE) AT 220-MHZ

The proton spectrum of poly(vinyl chloride) prepared by free-radical polymerization has been studied at 220 MHz and interpreted in terms of pentads for the α protons and tetrads for the β protons. The chemical shifts are in good agreement with those reported elsewhere using selectively deuterated polymers. The magnitudes of the vicinal coupling constants indicate that in the thermodynamically good solvents employed, the isotactic dyads are in approximate equilibrium between the conformations which, if repeated, result in a 31 helix, whereas syndiotactic dyads are probably in the conformation with the backbone in a planar zigzag structure. The tetrad and pentad relative intensities are consistent with Bernoullian chain propagation statistics, with a value Pm (the probability of isotactic placement) of 0.43. © 1969, American Chemical Society. All rights reserved.