New methodology to improve compatibility of PLA/PBAT blends using HO-PBAT-OH-initiated polymerization of lactide

A new methodology to fabricate the compatibilizer for PLA/PBAT blends through ring-opening polymerization of lactide using hydroxyl-terminated PBAT (HO-PBAT-OH) as macro-initiator in a high-shear reactor was developed. The modified polylactic acid (PLA-b) with weight-average molecular weights ( M w ) in the range of 1.42 × 10 5 to 2.96 × 10 5  Da were synthesized using 1%∼4% content of HO-PBAT-OH with M w of 4.86 × 10 5  Da. FTIR and NMR spectroscopy confirmed the covalent attachment of PBAT segments to the PLA backbone through ester linkages, establishing a well-defined block architecture. This block structure substantially improved the interfacial compatibility between PLA-b and PBAT, as evidenced by a refined morphology with reduced PBAT domain sizes and enhanced interfacial adhesion. DSC and DMA revealed a convergence of the glass transition temperatures ( T g ) of the two constituent polymers, indicating the improved miscibility. Rheological measurement also confirmed the improvement of miscibility through presenting a more coherent viscoelastic response. Notably, PLA-b/PBAT blends at a 70/30 wt% ratio exhibited a superior balance of mechanical properties compared to a conventional PLA/PBAT physical blend of the same composition, delivering a tensile strength of 42.6 MPa, an exceptional elongation at break of 280% and impact strength of 28.11 kJ/m 2 . This approach provides a simple and economically viable route to high-performance PLA/PBAT blends with an optimized combination of strength and ductility.