Stable Co-Continuous PLA/PBAT Blends Compatibilized by Interfacial Stereocomplex Crystallites: Toward Full Biodegradable Polymer Blends with Simultaneously Enhanced Mechanical Properties and Crystallization Rates

Constructing stable co-continuous morphology of commercial immiscible polymer blends remains an ongoing challenge in terms of complex presynthetic routes, multiple parameter dependency, and intrinsic instability of phase morphology. Herein, we demonstrate a full biodegradable polymer blend, poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate), where hitherto inaccessible co-continuous with asymmetric compositions (70/30) can be obtained with the assistance of interfacial stereocomplex crystallites (i-SCs) through reactive blending. By taking full advantages of this unprecedented compatibilizer, nanostructured co-continuous blends with synergistically enhanced comprehensive performance are achieved. First, due to the "rigid" i-SC, co-continuous morphology is induced through a simple melt blending procedure; second, considerable augmentation of the crystallization rate of the PLA matrix is accomplished on account of the in situ formed nucleation agent (i.e., i-SC); third, a super toughened material with simultaneously enhanced tensile strength, ductility, and impact strength can be acquired, resulting from the i-SC-induced co-continuous morphology; and fourth, i-SC can function as a "rigid" supporting layer between phases even above 200 °C, resulting in significantly enhanced morphology stability in melt. The versatile, facile, and practical strategy offers an industrially relevant technique to fabricate super-robust and fully biobased polymer materials.