Preparation of a main-chain azobenzene polyurethane and its application in photopatterning

Photo-responsive materials have attracted widespread attention for their potential advantages in resource conservation and sustainable use. Among the various photo-responsive molecules, azobenzene groups exhibit unique photoconductive cis-trans isomerization responsiveness and find extensive applications in the field of photo-controlled smart materials. This paper presents the preparation of a photo-responsive polyurethane material (denoted as PBHC6AB-U) incorporating azobenzene groups into its main chain. PBHC6AB-U exhibits outstanding photo-response performance, boasting a photo isomerization efficiency of 71.7%, and can achieve 20 cycles of the write-erase process under alternating UV and visible light irradiation. Moreover, by incorporating this material into A4 paper, one can prepare a photo-responsive erasable paper with a hydrophobic water contact angle of 110°, capable of multiple cycles of use. It possesses excellent photochromic and waterproof properties, showcasing a promising application prospect in the field of optical information storage.