Carbon Dots with Tailored Surface Wettability as Pickering Emulsifiers

Carbon dots (CDs) have attracted increasing attention in stabilizing Pickering emulsions due to their fascinating physicochemical properties. However, their practical use as Pickering emulsifiers has been limited due to the strong hydrophilic nature of the pristine CDs. Herein, the surface wettability of the CDs is simply tailored with hydrophobic hexyl isocyanates to produce surface-modified CDs (CD-Hs), and these are investigated as Pickering emulsifiers. Compared with the pristine CDs, CD-Hs showed strong adsorption at the oil-water interface, thereby exhibiting a high emulsification behavior. Furthermore, the effect of varying the density of hydrophobic hexyl isocyanates upon the emulsification behavior of the CD-Hs is investigated. Additionally, the practical applicability of the synthesized CD-Hs as the emulsifier is demonstrated in the Pickering emulsion polymerization process. Styrene-in-water emulsions stabilized by the CD-Hs are successfully polymerized to produce nanosized polystyrene (PS) particles with enriched fluorescent emission. Furthermore, the CD-stabilized PS particles exhibit adsorption performance toward heavy metal ions and organic dyes, demonstrating great potential for wastewater treatment. This study provides a promising approach for the design and fabrication of CD-based emulsion systems and hybrid materials.