Poly(butylene succinate) (PBS) is a bio-based and biodegradable aliphatic polyester that has attracted increasing interest as a sustainable binder for coating applications. Despite its favorable environmental profile, the moderate mechanical strength, thermal resistance, and barrier performance of PBS can restrict its use in demanding coating systems. In this study, biochar (BC), a low-cost carbon-rich material derived from biomass, was employed as a functional filler to tailor PBS properties, with emphasis on the role of biochar functionalization and its impact on coating-relevant performance. PBS/BC composites containing low biochar loadings were prepared via melt-mixing, an industrially scalable and solvent-free processing route. Mechanically and chemically functionalized biochar was incorporated to enhance filler dispersion and interfacial interactions with the polymer matrix. The effect of biochar functionalization on the structural, thermal, mechanical, and biodegradation behavior of PBS was systematically investigated. Crystallization behavior and thermal transitions were analyzed using differential scanning calorimetry (DSC) and X-ray diffraction (XRD), while tensile testing was employed to assess mechanical performance. The results show that appropriately functionalized biochar enhances stiffness, thermal stability, and crystallinity of PBS at low filler contents, indicating effective reinforcement and nucleation effects. These property enhancements, together with controlled biodegradation behavior, highlight the potential of PBS/biochar composites for sustainable coating applications requiring balanced performance and environmental compatibility.

Acknowledgements

The research work was supported by the project SUB1.1 Research Excellence Partnerships-REP, under the National Recovery and Resilience Plan Greece 2.0 (Strategy for Excellence in Universities & Innovation, ID 16289), Project CircLandfil, ID: ΥΠ3ΤΑ-0559411.