Tuning photoluminescence of polysiloxane functionalized carbon dots through changing polysiloxane compositions

Carbon dots (CDs) as the emerging carbon-based nanomaterials have great application potential in the optical devices and bioimaging fields. Due to their poor stability, the conventional CDs are prone to self-quenching and their photoluminescence is untunable. Herein, the polysiloxane functionalized CDs were prepared from the solvothermal reaction between citric acid and the polysiloxanes with different aminopropyl contents aiming to improve the stability and photoluminescence of CDs. The average size of the polysiloxane functionalized CDs ranged from 2.2 to 6.4 nm. The UV-visible absorption spectra of these CDs changed from long wavelength to short wavelength with the decrease of the aminopropyl content in the polysiloxanes. The fluorescence intensities and fluorescence cores of these CDs also varied with the aminopropyl contents in the polysiloxanes, which demonstrated that the photoluminescence of the functionalized CDs could be adjusted by the aminopropyl content in the polysiloxanes. When the aminopropyl content in the polysiloxanes was 50%-75%, the polysiloxane functionalized CDs possessed relatively high fluorescence quantum yield. The polysiloxane modification can effectively improve the stability of CDs and enable the tunable photoluminescence. This study provides a new strategy for improving the performances of CDs and is of importance for promoting the practical application of CDs.