Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
An FTIR spectroscopic study was carried out for rare-earth polyacetylenesIUPAC name: poly(vinylene). (PA) containing both Z (“cis”) and E (“trans”)We distinguish formally between configurations (Z, E = “cis”, “trans”) and conformations (cis, trans), though in the case of poly(vinylene) the physical quality is virtually the same. geometric isomers. Spectral assignments were made by the study of PA samples with different Z/E ratios and by referring to the known assignment of the IR spectrum of PA obtained with Ti(OC4H9)4·Al(C2H5)3. The conjugation effect of Z or E —CH=CH— sequences and their length distribution in PA are investigated by spectral subtraction and peak separation. It is shown that the frequency of v(CH) (out-of-plane deformation) is located in the regions 741 to 747 cm-1 and 940 to 1014 cm-1 for Z- and E-PA, respectively, depending on the conjugation length. At the beginning of thermal isomerization of Z-PA, long Z sequences are interrupted quite frequently; this causes a shift of v(CH) towards higher frequencies. In high E-PA obtained by thermal isomerization of Z-PA, uninterrupted long E sequences persist. This demonstrates that a crosslinking reaction between PA chains is not conspicuous during the thermal isomerization process.
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