Fully Bio-Based and Supertough PLA Blends via a Novel Interlocking Strategy Combining Strong Dipolar Interactions and Stereocomplexation

Optimizing interfacial compatibility is one of the core issues for constructing high-performance green poly(lactic acid) (PLA) blends. Herein, we prepared a poly(epichlorohydrin)-b-poly(D-lactic acid) (PECH-b-PDLA) diblock copolymer as an efficient compatibilizer for poly(L-lactic acid)/poly(epichlorohydrin) (PLLA/CHR) blends. The PECH-b-PDLA enabled the blends to form unique interlocks among the chains through combining the strong dipolar interaction and PLLA/PDLA stereocomplexation (SC). This strategy endows the PLLA/CHR blend with a unique co-continuous structure composed of CHR particles as the core and a bilayer shell formed by the PECH entanglement layer with strong dipolar interaction and a rigid SC thin layer. Physical properties of the blends were remarkably improved by a co-continuous structure with enhanced interfacial adhesion between phases. The optimum formulation showed unprecedented balanced mechanical properties: a nonbroken sample with an impact strength of 106.7 kJ/m2 and a high elongation at break of up to 467.2%; both were about 40 times those of pure PLLA. The interlocking mechanism through strong dipolar interaction and SC provides a broadly applicable and facile strategy to achieve PLA materials with superior properties for expanded industrial application.

Automated summary

In this study, a PECH-b-PDLA diblock copolymer was prepared as an efficient compatibilizer for PLLA/CHR blends, improving the interfacial adhesion and physical properties. The optimized formulation showed significantly enhanced impact strength and elongation, being 40 times those of pure PLLA.