A waterborne polyurethane-based fluorescent tunable carbon quantum dot

Fluorescent tunable materials have potential applications in lighting, display, anti-counterfeiting, biological probes, and so on. Herein, carbon quantum dots (CQDs) with blue fluorescence (BCDs), and yellow fluorescence (YCDs) were synthesized by solvothermal method using bio-based citric acid and lignin as carbon sources, respectively. BCDs and YCDs were anchored on polyurethane chains to prepare waterborne polyurethane-based blue fluorescent carbon quantum dots (BCDs 1.0 -WPU) and waterborne polyurethane-based yellow fluorescent carbon quantum dots (YCDs 1.0 -WPU), respectively. Compared with the corresponding BCDs and YCDs, the fluorescence intensity of both BCDs 1.0 -WPU and YCDs 1.0 -WPU is markedly enhanced, and the emission peaks obviously show a hypochromatic shift. A waterborne polyurethane-based fluorescent tunable carbon quantum dots (BCDs x YPDs 1-x -WPU) is prepared by mixing the ratio of BCDs 1.0 -WPU and YCDs 1.0 -WPU with the RGB method. It is noteworthy that BCDs x YCDs 1-x -WPU not only achieves a fluent change of fluorescence from blue to yellow but also emits strong white fluorescence (CIE coordinates: X = 0.28, Y = 0.32). The absolute value of the Zeta potential of BCDs x YCDs 1-x -WPU is greater than 40, indicating good storage stability. Furthermore, the thermal decomposition temperature is above 225 °C, implying good thermal stability. Furthermore, BCDs x YCDs 1-x -WPU uses water as a continuous phase and has potential applications in environmentally friendly luminescence, anti-counterfeiting and biological probes. Graphical