Multifunctional interface engineering: Tailoring mechanical and UV-resistant properties of PLA/PBAT-based composites via epoxy-functionalized carbon dots

Epoxy-functionalized carbon dots (OCDs) are synthesized via a hydrolytic condensation. • OCDs provide robust chemical interfacial bridges between PLA and PBAT. • Nanoscale OCDs cores refine the phase morphology via physical interactions. • Interfacial compatibility between PLA and PBAT is enhanced via a synergy of physical and chemical interactions. • OCDs give PLA/PBAT-based composites superior UV resistance. Biodegradable polymers like poly(lactic acid) (PLA) and poly(butylene adipate- co -terephthalate) (PBAT) hold significant promise for sustainable medical materials; however, their widespread application, particularly in demanding fields such as medical packaging materials, is hindered by inherent challenges including poor interfacial compatibility in blends and a general lack of functional properties like ultraviolet (UV) resistance. To address these limitations, this work introduced an innovative interfacial engineering strategy utilizing epoxy-functionalized carbon dots (OCDs) as a multifunctional compatibilizer for blending PLA and PBAT. The surface epoxy groups of OCDs underwent in-situ ring-opening reactions with terminal functional groups of PLA and PBAT during melt processing, establishing robust covalent bridges that fundamentally enhanced interfacial adhesion. This chemical compatibilization, synergized with the nanoscale effect of well-dispersed OCDs, led to a remarkable improvement in mechanical properties, with optimal increases of 47.7% in tensile strength and 23.4% in tensile modulus. Simultaneously, the intrinsic UV absorption of OCDs conferred exceptional UV-resistant capability to the PLA/PBAT-based composite, with absorption intensities at key wavelengths enhanced by up to 775%. Furthermore, the PLA/PBAT-based composites demonstrated modified thermal degradation behavior and improved melt strength. This multifunctional OCDs-filled PLA/PBAT composite integrated enhanced mechanical properties and excellent UV-resistant performance, demonstrating significant potential for advanced medical applications.