Achieving Rewritable Fluorescent Patterning on Dye-Doped Polymers Using Programmable Laser Direct Writing

There is an urgent need to broaden the new horizons of laser direct writing (LDW). Herein, the programmable rewritable laser fluorescent patterning on polymers was realized by doping dyes and CO2 laser LDW for the first time. The prepared fluorescent patterns had high brightness and high precision under 365 nm UV light. Importantly, the designed patterns could repeatedly be rewritten using CO2 laser. A series of poly(methyl methacrylate) (PMMA) doped with quinacridone (DClQA) dye were prepared to perform CO2 laser LDW and characterizations. Attenuated total reflection-Fourier transform infrared (ATRFTIR) spectroscopy revealed no generation of new compounds after LDW. Thermogravimetric analysis-Fourier transform infrared-gas chromatography-mass spectroscopy (TGA-FTIR-GCMS) indicated that the samples could be decomposed into complex products at high temperatures, and it also revealed no generation of any fluorescent substances. We confirmed the mechanism of the laser-induced fluorescence is that the dissociated DClQA molecules caused by the CO2 laser are more inclined to form hydrogen bonds with PMMA macromolecules, so that they cannot be restacked and recrystallized, leading to the disappearance of the intrinsic fluorescence quenching phenomenon of DClQA; thus, the fluorescence is naturally emitted. Benefiting from high precision, rewritable, and programmability, laser fluorescent patterning will have good application prospects in the field of polymer products anticounterfeiting.