Structural investigations on low‐molecular‐weight polyisobutenes

Abstract

Structural investigations of low-molecular-weight polyisobutenes synthesized by selective polymerization and of commercial polyisobutenes were made by 'H-and "C-NMR spectroscopy. It is possible to attribute the signals to "normal" and to some unusual olefinic structures. A comparison was made to literature data. ZUSAMMENFASSUNG:Mittels 'H-und I3C-NMR-Spektroskopie werden Strukturuntersuchungen an Polyisobutenen, die durch Selektivpolymerisation hergestellt wurden, und an Handelsprodukten durchgefuhrt. Es ist moglich, die Signale "normalen" und einigen ungewohnlichen Doppelbindungsstrukturen zuzuordnen. Die Ergebnisse werden mit Literaturdaten verglichen.

Thermally induced polymerization of isobutylene in the presence of SnCl4: Kinetic study of the polymerization and NMR structural investigation of low molecular weight products

“…It can be seen that the spectra of samples 1 and 2 are similar and markedly different from that of Oppanol B3. In our previous article,33 we assigned for Oppanol B3 two lines at 4.62 and 4.82 ppm to methylene protons in terminal structure A and the line at 5.13 ppm to methine proton in terminal structure B (see Scheme ), which is in accordance with other studies 19, 32, 34, 37–40. The spectra show that structures A and B also exist in samples 1 and 2; however, in contrast to Oppanol B3, the relative population of A structures is higher in these samples as can be seen from relative intensities of the corresponding lines.…”

“…Here, the pairs of lines at 114.45 ppm (CH 2 ) and 143.8 ppm (quaternary carbon), and at 128.0 ppm (quaternary carbon) and 135.55 ppm (CH) correspond to the terminal structures A and B, respectively 33, 38, 39–41. As was shown in our previous study,33 the pair of weak lines observed in sample 1 at 122.8 ppm (CH) and 133.8 ppm (quaternary carbon) corresponds to terminal structure C. This conclusion was confirmed by other studies 39, 40. By combination of APT and DEPT techniques, we have shown that a pair of lines at 121.5 and 133.3 ppm observed in spectra of both samples 1 and 2 belongs to two quaternary carbons, that is, to a tetrasubstituted double bond 33.…”

“…7). Moreover, structure C should provide a quartet in 1 H NMR spectrum 39. Therefore, the existence of the line at 5.10 ppm indicates the presence of another terminal structure with the trisubstituted double bond.…”

Comb-like polymers from macromonomers based on low-molecular-weight poly(isobutene)s

“…The results presented here and in the foregoing papers 14,15,18) show that functionalization reactions of low-molecular-weight poly(isobutene)s with high double bond contents are convenient possibilities to get polymerizable methacrylic derivatives as a pre-requisite for the synthesis of comb-like polymers also in a larger than a laboratory scale.…”

“…The poly(isobutene)s used, the structural composition of their end groups and other characteristics as well as the preparation of poly(isobutene)-based macromonomers were described in previous papers 14,15,18) . 4-(1,1,3,3-tetramethylbutyl) Alkylation and esterification procedures were described in 14) .…”