Reversible self-assembly of entrapped fluorescent gelators in polymerized styrene gel matrix: erasable thermal imaging via recreation of supramolecular architectures

Abstract

The reversible shift of emission in fluorescent molecular gelators has been explored for the preparation of a composite polymer film useful for erasable thermal imaging and secret documentation. A gelation-assisted photopolymerization of styrene allowed the entrapment of the fluorescent gelator molecules within a polystyrene matrix with a weak green fluorescence, which upon heating above the T_g of the polymer resulted in high-contrast fluorescence images due to the strong blue fluorescence of the individual molecules. The blue emission from the disassembled oligo(p-phenylenevinylene) molecules (OPVs) could be reversed to the green emission of the self-assembled OPVs by exposing the polymer film to chloroform vapors. The thermally written images are visible only under UV light and cannot be photocopied. A solvent-vapor-controlled recreation of the self-assembly of a fluorescent organogelator within a polymer matrix and its application in erasable secret documentation has not been reported previously.