Towards high-performance poly(L-lactide)/elastomer blends with tunable interfacial adhesion and matrix crystallization via constructing stereocomplex crystallites at the interface

In this work, we report a facile strategy to prepare super-tough and heat-resistant poly(L-lactide) (PLLA) blends by constructing stereocomplex (sc) crystallites with dual interfacial adhesion enhancer/matrix crystallization accelerator functionality at the interface of the blends of PLLA/ethylene copolymer. To exploit the dual functionality, poly(D-lactide) grafted ethylene-acrylic ester copolymer (EMA-g-PDLA) capable of collaborating with the PLLA matrix to form the sc crystallites was first prepared via melt coupling reaction between end groups (carboxyl and hydroxyl) of PDLA and excess epoxy group of EMA-glycidyl methacrylate copolymer (EMA-GMA). During subsequent melt-blending of PLLA with the prepared EMA-g-PDLA, sc crystallites are formed at the interface. The results show that, compared with PLLA/EMA-GMA and PLLA/EMA-g-PLLA blends, injection molded PLLA/EMA-g-PDLA blends have much higher impact toughness and heat resistance because the interface-localized sc crystallites can induce substantial enhancement in both interfacial adhesion and matrix crystallinity. More interestingly, by modulating the amount of sc crystallites at the interface of the blends, optimum impact toughness can be achieved due to the optimization of interfacial strength and matrix crystallinity. This work provides a new concept for the fabrication of high-performance PLLA blends by tailoring matrix and interface properties with the aid of sc crystallites.