Facile gram-scale synthesis of hydrophobic carbon quantum dots (CQDs) as a sustainable reinforcement for basalt fibre-reinforced polymer composites

Abstract

Nanocomposites offer superior mechanical properties, making sustainable nano-carbon reinforcements increasingly attractive due to their affordability and high specific strength. Carbon quantum dots (CQDs) are particularly promising due to their abundant precursors and tunable interfacial properties. However, traditional CQD synthesis often involves complex purification methods with low production yields and results in highly polar CQDs, limiting their compatibility with non-polar polymer matrices. To address these limitations, this work introduces hydrophobic CQDs with a production yield exceeding 85 % through a facile filtration-based purification process. These hydrophobic CQDs were readily dispersed in unsaturated polyester resin using simple mechanical stirring and sonication. The optimal inclusion of 0.5 wt% CQDs led to significant enhancements in tensile strength (72 %), flexural strength (43 %), and impact strength (51 %) compared to the pristine composite. Thermal characterization revealed that these improvements can be attributed to the effective modulation of the polymer microstructure, even at low CQD concentrations. Superior specific strength and enhanced toughness of CQDs reinforced composite are attractive attributes for their application in automotive body parts, impact resistant sports gear, and ballistic protection.