ISSN:
0098-1273
Schlagwort(e):
Physics
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The geometric structure of polymethylacetylene (PMA), polypentylacetylene (PPA), and poly(t-butylacetylene) (PTA) was investigated by 1H NMR, 13C NMR, and IR spectroscopies. It was shown that both NMR techniques can be used to determine the trans isomer content of PPA and PTA, whereas the 1H NMR and IR methods can be used for PMA. A calibration curve was constructed by using the 965- and 720-cm-1 bands of the IR spectrum of PPA, and could be used in future work for the same purpose if the samples had molecular weights similar to that of the one used in this study. The isomerization kinetics of PTA was investigated and cis→ trans activation energies of 88 and 121 kJ/mol were calculated in solution and in the solid state, respectively. Heat treatment of the PMA and PPA samples always leads to a cis→ trans isomerization with a 100% trans content under extreme conditions. Moreover, a cis→ trans isomerization of PTA was induced in CCl4, CDCl3, toluene, and benzene, but a trans→ cis isomerization was induced in decalin. The reversible isomerization of PTA covered a trans isomer concentration ranging form 25 to 60%.
Zusätzliches Material:
8 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1985.180231005
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