8-Hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) based high fluorescent, pH stimuli waterborne polyurethane coatings

8-Hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), a water-soluble pyrene dye, was used to develop highly fluorescent waterborne polyurethane (WPU) by physical dispersion in WPU matrix. The presence of negatively charged sulfonate ions in HPTS moiety assisted in homogeneous dispersion of HPTS in WPU matrix. The optical properties of HPTS-WPU emulsion and films were characterized by UV-Vis and PL spectroscopy and observed to exhibit high fluorescence property both in emulsion state as well as in solid state even at very low concentration. The fluorescence intensity was found to increase with increasing weight % of the HPTS dye in WPU matrix. Further, pH sensing behavior of these films was also investigated by exposing to trifluoroacetic acid (TFA) vapor (pka = 0.23) and ammonia (NH3) vapor (pkb = 9.25). Observations revealed that HPTS retained not only its highly green fluorescent nature in WPU matrix but also exhibited pH sensing behavior. The overall analysis suggested that HPTS-WPU could be used to develop an environmentally friendly high fluorescent smart coatings and textiles inheriting real-time pH sensing property. (C) 2017 Elsevier Ltd. All rights reserved.