title: Rewritable phosphorescent paper by the control of competing kinetic and thermodynamic self-assembling events.
abstract: Security inks have become of increasing importance. They are composed of invisible substances that provide printed images that are not able to be photocopied, and are readable only under special environments. Here we report a novel photoluminescent ink for rewritable media that dichroically emits phosphorescence due to a structural bistability of the self-assembled luminophor. Long-lasting images have been developed by using conventional thermal printers, which are readable only on exposure to ultraviolet light, and more importantly, are thermally erasable for rewriting. Although thermally rewritable printing media have already been developed using visible dyes and cholesteric liquid crystals, security inks that allow rewriting of invisible printed images are unprecedented. We realized this unique feature by the control of kinetic and thermodynamic processes that compete with one another in the self-assembly of the luminophor. This strategy can provide an important step towards the next-generation security technology for information handling.
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kishimura
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Takuzo
authors.initials: T
authors.lastname: Aida
mesh_terms: D003460:Crystallization / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D007281:Ink; D007700:Kinetics; D049408:Luminescent Agents / Q000032:analysis / Q000737:chemistry* / Q000528:radiation effects*; D008163:Luminescent Measurements; D008422:Materials Testing; D010209:Paper; D011327:Printing / Q000379:methods*; D011356:Product Labeling / Q000379:methods*; D012637:Security Measures; D013816:Thermodynamics; D014466:Ultraviolet Rays
chemical_list: D049408:Luminescent Agents