Evolution of Core−Shell structure in PLA/PBAT-g-GMA/TPS ternary blends via multi-Indicator molecular simulations

This study utilized molecular dynamics simulations to incorporate a poly(lactic acid) (PLA) matrix, poly(butylene adipate-co-terephthalate) modified with glycidyl methacrylate (PBAT-g-GMA), and thermoplastic starch (TPS) into an amorphous unit cell via a one-step blending method. Additionally, five PLA/PBAT-g-GMA/TPS (70/30/0, 70/25/5, 70/20/10, 70/15/15, 70/10/20) amorphous unit cells were created using a stepwise blending method. The radial distribution functions, hydrogen bond distribution, cohesive energy density, mixing energy, and diffusion coefficient of the blend components were analyzed. The optimal composition, identified through simulations, was subsequently prepared, and its glass transition temperature (T g ) was determined using differential scanning calorimetry (DSC). The fracture surface was examined via scanning electron microscopy (SEM). Results showed that the one-step blending model did not form a distinct core-shell interface, whereas higher PBAT ratios in the stepwise blending model exhibited clearer core-shell interfaces. The 70/20/10 composition model exhibited the highest mixing energy (1067.0 kcal/mol). The number of hydrogen bonds at the PBAT-TPS interface was maximized in this model, indicating the strongest interfacial interaction. The predicted T g of the 70/20/10 composition model was 59.9 °C, differing by only 0.6 °C from the measured value. The core-shell structure was observed on the frozen fracture surface, confirming the reliability of the model predictions. This study systematically analyzed the formation, distribution, and interaction of the core-shell interface in the PLA-based ternary blend system using molecular dynamics simulations and multi-indicator analysis. An optimal blending ratio was identified, providing a theoretical foundation for future material design and optimization.