Interface-directed assembly of a carbon quantum dots@titanium dioxide nanonetwork for synergistic enhancement of poly(lactic acid) composites

Poly(lactic acid) (PLA), a biodegradable polyester derived from renewable feedstocks, exhibits inherent brittleness, limited thermal stability, and uncontrolled degradability, which restricts its broader application as a sustainable biomaterial. Constructing robust and well-organized interfacial architectures offers an effective strategy to overcome these challenges. In this study, a rationally designed carbon quantum dots (CQDs)@titanium dioxide (TiO 2 ) nanonetwork was employed to reinforce PLA composites and elucidate how CQDs@TiO 2 modulates their structural features, interfacial characteristics, and overall properties. It was demonstrated that embedding CQDs@TiO 2 into PLA accelerated its degradation behavior in hydrolysis, phosphate-buffered saline (PBS) immersion, and soil burial tests. Meanwhile, the thermal resistance, overall thermal stability, and crystallization behavior of PLA were substantially enhanced due to the nucleation and thermal barrier effects of the CQDs@TiO 2 nanonetwork. Moreover, the uniform morphology and compatibility of CQDs@TiO 2 enabled homogeneous dispersion and effective stress transfer in PLA, leading to simultaneous enhancements in tensile modulus, strength, elongation, and toughness. Specifically, the tensile modulus, tensile strength, and elongation at break of PLA/CQDs@TiO 2 composites increased by 11%, 44%, and 107%, respectively, compared to pure PLA. This study provides an efficient and sustainable strategy for tailoring the mechanical, degradability, and thermal properties of PLA composites.