Compatibilization of biopolymer blends: a review

Biopolymers from renewable bio-based resources provide a sustainable alternative to petroleum-derived plastics, but limitations like brittleness and cost restrict applicability. Blending offers an affordable route to combine the advantages of different biopolymers for tailored performance. However, most biopolymer pairs are intrinsically immiscible, necessitating compatibilization to obtain optimal blend morphology, interfacial interaction, and properties. This review summarizes key compatibilization strategies and recent advances in tailoring biopolymer blends. Non-reactive techniques using block or graft copolymers can increase compatibility, though property enhancements are often modest. More impactful are reactive methods, which functionalize and form compatibilizing copolymers in-situ during melt-blending. Nanoparticle incorporation also effectively compatibilizes through interface localization and morphology control. These strategies enable significant toughening and compatibilization of poly(lactic acid) (PLA) and other brittle biopolyesters by blending with ductile polymers such as poly(butylene adipate-co-terephthalate)((PBAT) or elastomers like natural rubber. Properly compatibilized PLA blends exhibit major simultaneous improvements in elongation, strength, and impact resistance. Using inexpensive starch decreases cost but requires compatibilization to maintain adequate properties. Nanoparticles additionally impart functionality like barrier and flame retardance. However, quantitatively correlating interaction, processing, morphology, and properties will enable further blend optimization. Developing tailored reactive chemistries and nanoparticles offers potential beyond conventional techniques, and retaining biodegradability is also crucial. Overall, compatibilization facilitates synergistic property combinations from complementary biopolymers, providing eco-friendly, high-performance, and cost-effective alternatives to traditional plastics across diverse applications.