Thermal cis–trans isomerization of cis–transoidal polyphenylacetylene

Solution and solid‐state thermal cis‐trans isomerization of cis–transoidal polyphenylacetylene was investigated. At temperatures higher than 120°C, cis‐trans thermal isomerization in solution is accompanied by cyclization, aromatization, and scission of the polymer chain. Both spectral and kinetics data showed that at temperatures lower than 120°C, not only cis‐trans thermal isomerization takes place but also intramolecular cyclization.