Enhancing interfacial compatibility and performance of polylactic Acid/ poly(butylene adipate-co-terephthalate) blends via innovative reactive compatibilization.

With the increasing global demand for sustainable materials, the development of high-performance bio-based polymer blends has become a critical direction in materials science research. To address environmental pollution and resource depletion, this study introduces poly(propylene glycol) diglycidyl ether (PPGDGE) as a reactive compatibilizer for the first time. Using melt blending technology, PPGDGE was blended with poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) at a mass ratio of 70:30 to prepare a PLA/PBAT/PPGDGE (PBP) ternary blend system. The effects of PPGDGE on the multifaceted properties of the PLA/PBAT blend were systematically evaluated. The study found that the epoxy groups in PPGDGE can undergo ring-opening reactions with the nucleophilic end groups of PLA and PBAT, generating PLA-graft-PBAT copolymers in situ at the interface, thereby improving the compatibility of the blend to some extent. As the PPGDGE content in the system gradually increased, the processing, optical, and thermal properties of the blend improved progressively, while the notched impact strength and elongation at break first increased and then decreased. When the PPGDGE content reached 5 phr, the difference in glass transition temperatures (ΔTg) of the blend reached its minimum. SEM images showed that the PBAT dispersed phase achieved the smallest size and most uniform distribution, while AFM revealed the smoothest surface and most continuous phase structure, indicating optimal compatibility between PLA and PBAT at this loading. At this point, the light transmittance and Vicat softening temperature of the blend increased from 76.8 % and 82.6 °C to 90 % and 88.8 °C, respectively, while the elongation at break and notched impact strength rose to 480.07 % and 14,370.34 J/m2-4 times and 3.5 times higher than those of the blend without PPGDGE, respectively. The toughness of the blend was significantly enhanced, and the fracture surface exhibited the highest roughness, displaying clear ductile fracture characteristics. Meanwhile, in vitro cell experiments (L929 cells) confirmed that all PBP blends possessed excellent biocompatibility: live/dead staining showed high-density clusters of live cells and minimal dead cells on and around the material surface, while CCK-8 assays demonstrated stable and continuous cell proliferation on the blend surfaces (p < 0.05), with no negative impact on cell viability from PPGDGE addition. Regarding degradation performance, the polyether segments in PPGDGE imparted significant hydrophilicity, effectively promoting water molecule penetration and diffusion within the matrix and accelerating ester bond hydrolysis, thereby substantially increasing the blend's degradation rate (the absolute value of the mass loss rate constant k over time increased from 0.5711 to 0.8582). In summary, the introduction of PPGDGE not only effectively enhanced the mechanical, thermal, and optical properties of the PLA/PBAT blend but also ensured excellent cytocompatibility and tunable degradation rates, laying a theoretical foundation for its broad application in PLA-based biodegradable materials where predetermined service life and biosafety are equally critical.