An environmentally friendly PET-based Carbon Dots (PET-CDs) with excellent fluorescence properties were prepared with waste PET bottle, pyromellitic acid and ammonia water as raw materials by one-step hydrothermal method. The preparation mechanism of PET-CDs was as follows: PET first underwent ammonolysis reaction to produce terephthalic acid diamide and ethylene glycol, and then dehydrated and carbonized with pyromellitic acid to form PET-CDs. The as-prepared PET-CDs exhibit excitation-independent emission properties in the range from 340 to 440 nm, and the fluorescence quantum yield is as high as 87.36%. In terms of structure, PET-CDs is a spherical structure with an average particle size of 2.0 nm, and its surface contains carboxyl and amino groups. The PET-CDs were dispersed in a PVA matrix to obtain an light blocking films(LBFs) for 250-450 nm light with excellent properties, and its transparency for 450-700 nm light is good. In addition, PET-CDs was used in the fields of LED, and it was found that the color coordinate for the LED assembled with PET-CDs and 395 nm LED chips is (0.55, 0.44) and the correlated color temperature is 2018 K.
Keywords: Carbon dots; Fluorescent anti-counterfeiting; Light blocking film; Mechanism; PET waste.
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