Photoresponsive polyurethane–acrylate block copolymers. II. Photomechanical effects in copolymers containing 6′-nitro spiropyranes and 6′-nitro-bis-spiropyranes

✍ Scribed by Eduardo A. Gonzalez-De Los Santos; Ma. Josefina Lozano-González; Anthony F. Johnson

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 166 KB
• Volume: 71
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19990110)71:2<267::aid-app10>3.0.co;2-z

✦ Synopsis

The photochromic effect of polyurethane-acrylate block copolymers containing 6Ј-nitro spiropyranes and 6Јnitro-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.