Enhanced fluorescence of nano polyethylene glycol derived from the oxidation

The newly emerging fluorescent materials attracted extensive interests such as carbon quantum dots or nano dots. When the fluorescent mechanism was discussed contribution of oxidation of starting materials for the fluorescence was neglected usually. Herein, fluorescent polyethylene glycol nano particles (PEG NPs) could be prepared when the solution was suffered from a convenient oven-heating at 100 °C for 60 min and the fluorescent quantum yield reached as high as 13.67% while PEG solution had none of fluorescence as is known to all. Measurements of infrared and X-ray photoelectron energy spectra illustrated the oxidation of PEG during the heating disposing. The fluorescent intensity could be improved successively at the presence of hydrogen peroxides or cobalt ions respectively. Such an intensive oxidation even resulted in generation of the carbon quantum dots. However, the added hydroquinone, as an antioxidant, prohibited the increase of fluorescence. Such evidences disclosed that oxidation was the key step for the fluorescence and for the formation of carbon quantum dots.