POLYMER NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY .18. NUCLEAR MAGNETIC RESONANCE SPECTRUM, DIMENSIONS, AND STERIC INTERACTIONS OF ISOTACTIC POLYPROPYLENE

The 220-MHz proton nmr spectrum of a highly isotactic sample of polypropylene has been examined and interpreted in detail. The polymer was shown to contain 2 % racemic dyads occurring randomly at junctions of isotactic sequences of opposite configurations. The mean-square end-to-end distance of this polymer was measured under 9 conditions, and comparison of the value obtained with theoretical predictions of Flory, Mark, and Abe11 permitted an approximate measurement of the strength of steric interactions within the polypropylene chain. Additional information on the steric interactions was obtained from a comparison of the chemical shifts of racemic dyads in isotactic and syndiotactic chains. © 1969, American Chemical Society. All rights reserved.