Photoresponsive Polyurethane-Acrylate Block Copolymers.II.Photomechanical Effects in Copolymers Containing 6'-Nitro Spiropyranes and 6'-Nitro-bis-Spiropyranes

摘要

The photochromic effect of polyurethane-acrylate block copolymers con-taining 6'-nitro spiropyranes and 6'nitro-bis-spiropyranes has been investigated.The influence of incorporation of the photochromic agent into the polymeric matrix as a simple solid solution or via a chemically bonded form and the effect of the composition rate (polyurethane-acrylate) of the block copolymer were studied.In general,it was observed that the photoresponse (photomechanical effect) for the spiropyranes and,especially,the bis-spiropyranes is influenced by a combination of several factors,primarily,the spatial and electronic differences between the two forms (Sp.-Mer.) in the photoisomerization of these compounds.Such factors are discussed here.