Advanced Study on Synthesis and Optical Performances of a Waterborne Polyurethane-based Polymeric Dye

A waterborne polyurethane-based polymeric dye (WPU-CFBB) was synthesized by anchoring 1, 4-
bis(methylamino)anthraquinone (CFBB) to waterborne polyurethane chains. The number molecular
weight, glass transition temperature and average emulsion particle size for the polymeric dye were
determined, respectively. This polymeric dye exhibited intriguing optical behaviors. The polymeric dye
engendered two new absorption bands centered at about 520 nm and 760 nm if compared with CFBB
in UV-vis spectra. The 760 nm peak showed hypsochromic shift with the decrease of average particle
sizes. The polymeric dye dramatically demonstrated both hypsochromic and bathochromic effects
with increasing temperature. The fluorescence intensity of the polymeric dye was much higher than
that of CFBB. It was found that the fluorescence intensities would enhance from 20°C to 40°C and
then decline from 40°C to 90°C. The fluorescence of the polymeric dye emulsion was very stable and
was not sensitive to quenchers.