Abstrakt
High-cis poly(phenylacetylene) (PPhA) has been prepared by polymerization of phenylacetylene with [Rh(COD)acac] catalyst and its molecular weight (MW) and configurational stability studied by SEC, (1)H NMR, UV/vis and IR techniques. PPhA dissolved in THF and THF-d(8) and exposed to the atmosphere and daylight at room temperature was found to undergo simultaneous cis-trans isomerisation and oxidative degradation accompanied by formation of a small amount (similar to 2 wt. %) of 1,3,5-triphenylbenzene.
The extent of 1,3,5-triphenylbenzene formation was at least one order of magnitude lower than the extent of formation of new (shorter) PPhA macromolecules via their scission from the longer ones. Preparative MW-based fractionation revealed that a partly aged PPhA contains both (i) deeply isomerised macromolecules (forming the lower-MW fraction) and (ii) microstructurally unperturbed high-cis macromolecules (forming the higher-MW fraction).