Epoxy-functionalized cellulose nanocrystals for simultaneous compatibilization and 3D printability enhancement in PLLA/PBAT blends

Cellulose nanocrystals (CNCs) hold great potential as nanofiller compatibilizers for immiscible poly( L -lactic acid) (PLLA) and poly(butylene adipate-co-terephthalate) (PBAT) blends. However, a key challenge remains the precise engineering of CNC surface chemistry to achieve strong interfacial interactions and selective localization. In this study, a novel multifunctional compatibilizer was developed based on CNCs grafted with a poly(vinyl acetate-co-glycidyl methacrylate) (P(VAc-co-GMA)) copolymer. The PVAc segments ensure thermodynamic compatibility within the PLLA matrix, while the epoxy groups from GMA offer reactive sites for in-situ interfacial compatibilization. By tuning the comonomer ratio, the surface energy of the grafted CNCs was tailored to match that of PLLA, promoting excellent dispersion during melt processing. The modified CNCs effectively compatibilized the PLLA/PBAT blend, reducing the PBAT domain size from 3.27 µm to 2.00 µm. Moreover, covalent bonds formed between the polymers and CNCs enhanced the melt strength and complex viscosity of blends. Furthermore, the improved processability was directly reflected in the printability. The compatibilized blend exhibited excellent performance in fused deposition modeling (FDM), producing parts with improved dimensional accuracy and interlayer adhesion. Overall, this work offers a facile and effective strategy for designing reactive CNC-based additives that enable simultaneous compatibilization and performance enhancement of PLLA/PBAT blends, facilitating their application in sustainable manufacturing and advanced 3D printing.