Facile preparation of fluorescent non-conjugated polymer films with tunable multicolor photoluminescence via layer-by-layer assembly

Abstract

Fluorescent non-conjugated polymeric films have remarkable advantages for ion sensing but have been less explored. Herein, fluorescent non-conjugated polymeric multilayers of poly(acrylic acid) (PAA)/polyethylenimine (PEI) with tunable multicolor photoluminescence are prepared using a simple and versatile layer-by-layer assembly (LbL) method. The PAA and PEI polymers do not have typical conjugated fluorescent units, but (PAA/PEI)*n multilayers display strong blue, green, and red fluorescence in the visible region. Interestingly, (PAA/PEI)*n multilayers exhibit different sensitivities to metal ions based on fluorescence quenching. This kind of LbL-assembled (PAA/PEI)*n multilayers provides a new perspective to prepare fluorescent non-conjugated polymeric films, and it avoids the complicated synthetic route and possesses good photo stability and excellent biocompatibility.