Simple method to prepare fluorescent silicon rubber by melt-compounding with crude carbon dots fluid

Carbon dots (CDs) have attracted increasing attention as fluorescent agents for elastomer composites. Bottom-up synthesis of carbon dots (CDs) from molecular precursors would inevitably produce crude carbon dots (CCDs), i.e., a mixture of CDs, quasi CDs, polymer clusters, and molecular fluorophores. The CCDs are normally subjected to purification processes to obtain the pure CDs, while the purification procedures are time-consuming, expensive, and difficult to be scale-up. Herein, we directly used the CCDs as the fluorescent agents for silicon rubber. To achieve a good CCDs dispersion within the polymer matrix, we firstly prepared the CCDs fluid by mixing the CCDs solid with water, then the CCDs fluid was melt-mixed with the SiR (with the silica as filler) by a two-roll mill. The results revealed that small amounts of CCDs (less than 1 phr) could endow the matrix with intriguing luminescent property. Overall, this work offers a green and facile strategy to use CCDs as low-cost fluorescent agents for the SiR through melt-milling of CCDs fluid and rubber, which can be extended to a variety of other melt-processable polymer matrices (such as millable polyurethane rubber) and enables a broad range of potential applications.