TPMS-based PLA/PETG interpenetrating composites: The synergistic enhancement of mechanical properties for bone implant

Maxillofacial bone repair demands implants that match native mechanics, yet conventional designs struggle to balance strength and toughness. We present an interpenetrating phase composite (IPC) that couples a PLA lattice with a PETG network, printed via multimaterial FDM into P-type TPMS architectures with offset thickness d = 0.4–1.2 mm. The IPC shows a synergistic “1 + 1 > 2” effect: versus porous PLA, compressive strength increases by 153–244 %. Finite-element analysis reveals more uniform stress fields and delayed local buckling under compression. A modified dual-phase Gibson–Ashby model predicts elastic modulus and yield strength across densities and compositions, with good agreement to experiments. Calcein-AM/PI and CCK-8 assays indicate high cell viability and negligible cytotoxicity. ALP activity and Alizarin Red staining support preserved osteogenic potential, while short-term subcutaneous implantation demonstrates favorable tissue responses with neovascularization and collagen remodeling. Simulated body-fluid immersion shows composition-dependent, predictable hydrolytic behavior. Collectively, the rigid–flexible coupling of PLA/PETG IPC TPMS structures yields concurrent gains in strength, toughness, and energy absorption with reassuring biosafety, positioning this platform as a promising option for load-bearing, patient-specific craniofacial implants and offering a practical framework for performance prediction and design optimization.