Photochemistry and photophysics of copolymers of (−)menthyl acrylate with 4-hydroxystilbene acrylate

Copolymers of trans-4-hydroxystilbene with (—)menthyl acrylate exhibit upon irradiation transåcis isomerization of the side-chain stilbene chromophores analogously to trans-4-hydroxystilbene-2-methylpropanoate, chosen as low molecular weight model compound. U.v. measurements on polymer samples indicate a deviation from first-order kinetics. In the fluorescence spectra of all-trans polymer samples both excimer and monomer emissions are observed. On irradiation the excimeric component is quenched much faster than the monomeric one. Fluorescence polarization experiments indicate a higher conformational rigidity of the stilbene chromophore when inserted in polymeric systems. Comparison of chiroptical properties of both unirradiated and irradiated copolymers suggests that on irradiation a local conformational rearrangement of macromolecules takes place.