NMR data on the stereoregularity of polypropylene

Abstract

following deuterated propylenes have been run on a Varian HA 100 spectrometer: NMR spectra of isotactic, predominantly syndiotactic, and atactic polymers of the CD, H CD, D D D D H D HDadurch war es moglich, eine untere Grenze fiir die sterische Reinheit von isotaktischem Polypropylen anzugeben; ferner wurde gesichert, daB alle Permanenzen stets von der cis-Offnung der Monomereinheiten herriihren, schliel3lich konnten Hinweke fiir den EinfluB von Tetraden auf das NMR-Spektrum der Methylenprotonen gefunden werden.

Reinvestigation of the steric structure of poly(methyl propenyl ether) obtained by cationic catalysts

“…[(I) and (11) are shown in a planar zig-zag formula which is different from Fischer-projection formula in the previous papers (1,5 The PMPE prepared from the trans-isomer gave a more intensive peak on the high-field side than the low-field side as shown in Figure 1. On the other hand, in the methylene group of isotactic polypropylene (11), a peak of antiproton was observed in a lower field than that of syn-proton (6). As the amethine proton in (I) corresponds to anti-proton in (11) when an isotactic sequence is depicted in a planar zig-zag conformation, the assignment of the amethme resonance of PMPE seems to be contradictory to that of the methylene resonance of polypropylene.…”

Nuclear Magnetic Resonance Spectroscopy in Macromolecular Science

“…Naturally, stereochemical effects were of great interest to G. Natta and his coworkers, who took advantage of the new technique to elucidate the stereoregularity of poly(propylene). [21] With the 100 MHz spectrometer at their disposal, isotactic, heterotactic and syndiotactic triads could be evidenced. With the advent of 13 C NMR, the study of stereochemical configuration experienced another boost, because of the higher spectral dispersion and the fact that 13 C chemical shifts can effectively be rationalized in terms of the g-gauche effect.…”

Conformational energies, stereoregularity, and the role of nonstaggered conformations in polymer chains

“…The statistical weight matrices with the four states indexed in the stated order are where u* and w* retain the same significance as in the treatment of polymethylene ab0ve.t For the purpose stated above, Mark, Abe, and Flory14 calculated characteristic ratios using eqs. (5) and (6). The values obtained in this manqer were only slightly greater than were calculated correspondingly on the t The element for the g*lg* state in eq.…”