Integrated design of multifunctional reinforced bioplastics (MReB) to synergistically enhance strength, degradability, and functionality†

Abstract

Bioplastics have emerged as a tangible solution to the plastic waste crisis. However, current bioplastics like polyhydroxybutrate (PHB) are notorious for their brittle properties, poor durability, limited functionality, and relatively slow biodegradation, all of which prevent broader applications to fulfill their environmental benefits. We have hereby addressed all aforementioned challenges synergistically by designing Multifunctional Reinforced Bioplastics (MReB). Computational modeling has guided the MReB design to take advantage of the complementary properties of PHB and cellulose nanofibrils (CNF) via cross-linking the two biopolymers with toluene-2,4-diisocyanate (TDI). The MReB design significantly improved the mechanical properties of bioplastics, enabled multi-functionality, and enhanced biodegradability. Both the crystallinity and thermal stability of the films were enhanced in the MReB design. The highest tensile strength of 21.5 MPa with a Young's modulus of 4.63 GPa was achieved in MReB. MReB films also achieved substantially improved water stability, printability, and air impermeability, all of which have promoted broad applications of MReB. Furthermore, MReB showed faster degradation as compared to PHB and nanocellulose films alone and degraded as larger pieces, and avoided forming micro-pieces leading to microplastics. Metagenomic analysis revealed that the recruitment of cellulose-degrading microorganisms might have accounted for the improved PHB degradation in the composite. The MReB materials thus represented a transformative advancement in biopolymer-based plastic products, enabling drastically enhanced multifaceted performance for broader applications while mitigating environmental impact. The new mechanisms could guide the future development of composites with enhanced mechanical and biodegradable properties.