Waterborne Polyurethanes with Tunable Fluorescence and Room-Temperature Phosphorescence.

Single-component materials with both fluorescence and room-temperature phosphorescence (RTP) are useful for ratiometric sensing and imaging applications. On the basis of a general design principle, an amino-substituted benzophenone is covalently incorporated into waterborne polyurethanes (WPU) and results in fluorescence and RTP single-component dual-emissive materials (SDMs). At different aminobenzophenone concentrations, the statistical, thermal, and optical properties of these SDMs are characterized. Despite their similar thermal behaviors, the luminescence properties as a function of the chromophore concentration are quite different: increasing concentrations led to progressively narrowed singlet–triplet energy gaps. The tunability of fluorescence and RTP via chromophore concentration is explained by a previously proposed model, polymerization-enhanced intersystem crossing (PEX). The proposal of PEX is based on Kasha’s molecular exciton theory with a specific application in polymeric systems, where th...