Multi-stimuli-responsive fluorescence of AEE polyurethane films

Polyurethanes STMPU and HTMPU containing AIE fluorogens in the soft segments and hard segments, respectively, have been synthesized and characterized. Both two resulting polyurethane solutions exhibited an aggregation-enhanced emission (AEE) feature. Then two kinds of polyurethane films were prepared and their multi-stimuli-responsive properties were explored. Interestingly, the fluorescence emission of two polyurethane films were decreased in high temperature, and polyurethanes with different structures have different temperature-dependent fluorescent behaviors. Meanwhile, weak emission was obtained when acetone was dripped onto the two polyurethane films. Moreover, the fluorescence of the polyurethane STMPU film was greatly enhanced with the increase of tensile stress (at epsilon < 0.3), suggesting its potential application in multifunctional fluorescent probes.