Enhancing the mechanical properties of biodegradable PLLA/PBAT blends for 3D filament via one-pot synthesized CNCs-PVAc powder

The combination of polymer blends and nanofillers is an effective strategy for creating high-performance polymer alloys with a hierarchical structure. Herein, a one-pot synthesized polyvinyl acetate-modified cellulose nanocrystal (CNCs-PVAc) powder was used, without removing the ungrafted homopolymer, to enhance the properties of a poly (L-lactic acid) (PLLA)/poly (butylene adipate-co-terephthalate) (PBAT) blend for 3D filament via a simple melt-extrusion process. Compared with neat PVAc-grafted CNCs (CNCs-g-PVAc), it was found that the presence of ungrafted PVAc homopolymer is helpful for promoting the dispersion of CNCs in the PLLA/PBAT blend, leading to an improvement in both strength and toughness, as well as a decrease in the domain size of the PBAT disperse phase. Notably, the synergism of CNCs-PVAc and strong shear action in fused deposition modeling (FDM) resulted in the formation of highly oriented PBAT nanofibers in PLLA/PBAT/CNCs-PVAc nanocomposites, thereby contributing to the strength-toughness balance of 3D print objects. The tensile breaking energy and notch impact strength (90° infilled) of the prepared 3D print objects were enhanced by 896% and 969%, respectively, compared with pure PLLA. Additionally, the designed nanocomposites exhibit outstanding biodegradability, biocompatibility, and shape-memory properties, making them suitable for medical vascular clips and strong-toughness load-bearing frames.