Chiroptical and photochromic properties of stereoregular copolymers of 4-methacryloxyethylenoxyazobenzene with (-)-menthyl methacrylate

Copolymers of the photochromic monomer 4-methacryloxyethylenoxyazobenzene with the optically active comonomer (-)-menthyl methacrylate, having different stereoregularity, were investigated in order to obtain a better understanding of the relationship between microstructure and photochromism in synthetic macromolecules. No appreciable effect was observed by copolymer composition, sequence distribution, and microtacticity on the photoinduced trans --> cis isomerization of the azobenzene side chains. This last, however, is reflected in changes of the chiroptical properties, type and entity of the photoinduced variation being dependent on chain structure. The long spacer separating the azo chromophore from the main chain limits the extent of chiroptical properties dependence on irradiation.