Synthesis and fluorescence enhancement behavior of a novel fluorescent aqueous polyurethane emulsion DDAQ-TDI-PU

A novel fluorescent aqueous polyurethane emulsion DDAQ-TDI-PU was synthesized by blocking the anthraquinone moiety of 1,4-diamino-2,3-diphenoxyanthraquinone (DDAQ) into polyurethane chain using 2,4-tolylene diisocyanate (TDI), poly(propylene glycol) and 2,2-dimethylol propionic acid. The chain structure of DDAQ-TDI-PU was confirmed by means of Fourier transform infrared spectroscopy and UV–vis analysis. Comparing to the UV–vis spectrum of DDAQ, DDAQ-TDI-PU showed a hypsochromic shift from the absorption maxima of 518, 558, 609 nm to 510, 548, 586 nm, respectively. It was found that the fluorescence intensity of DDAQ-TDI-PU emulsion was enhanced greatly comparing with that of DDAQ. The fluorescence of DDAQ-TDI-PU was very stable not only for the long term storage but also for the fluorescence quencher.