SEC/DAD and 1H NMR Study of Molecular Weight and Configurational Stability of Poly(2,4-difluorophenylacetylene) and Polyphenylacetylene Prepared with Rh Catalyst

Newly prepared high-cis poly(2,4-difluorophenylacetylene) is found to undergo simultaneous cis-to-trans isomerization and degradation during aging in THF-d(8) solution exposed to the atmosphere. Partly aged polymers contain two microstructurally differing fractions: deeply isomerized macromolecules of lower MW and microstructurally unperturbed high-cis macromolecules of higher MW. SEC/DAD provides an unambiguous distinction and UV-Vis characterization of these fractions. The non-uniform MW distribution of isomerized and high-cis macromolecules is assumed to result from acceleration of degradation of polymer chains by simultaneous cis-to-trans isomerization.