Biodegradable Dual‐Material 4D ‐Printed Scaffolds With Tunable PLA / PEG Ratios for Mandibular Bone Regeneration

ABSTRACT In this study, biodegradable dual‐material 4D‐printed scaffolds with tunable poly(lactic acid)/poly(ethylene glycol) (PLA/PEG) ratios were designed, fabricated, and systematically characterized for mandibular bone regeneration. By combining compositional grading with architectural grading, the scaffolds were engineered to mimic the hierarchical cortical–cancellous structure of native bone, featuring a dense, low‐PEG cortical shell and a porous, PEG‐rich cancellous core with gyroid architectures at varying infill densities. Thermal and chemical characterization (FTIR, DSC, and TGA) confirmed that PLA and PEG interact primarily through physical hydrogen bonding, with PEG acting as a plasticizer that lowers the glass transition temperature and enhances chain mobility without compromising thermal stability. SEM analysis revealed a composition‐dependent transition from brittle to ductile fracture morphologies, consistent with the observed mechanical response. Mechanical testing showed that compressive strength is governed mainly by cancellous infill density and PEG content, while the elastic modulus is dominated by the cortical shell, enabling decoupling of stiffness and strength. All scaffolds exhibited reliable shape fixity and thermally triggered recovery, confirming robust 4D functionality, and in vitro degradation studies demonstrated tunable mass loss controlled by PEG content and porosity. Among all configurations, the scaffold comprising a PLA/PEG 95/5 cortical shell and a PLA/PEG 80/20 cancellous core with 40% gyroid infill provided the most balanced combination of mechanical stability, body‐temperature‐responsive shape recovery, and controlled biodegradation, highlighting its potential for minimally invasive, self‐fitting mandibular defect repair.