Dynamic Boronate Ester Chemistry Facilitating 3D Printing Interlayer Adhesion and Modular 4D Printing of Polylactic Acid

Abstract 3D printing, such as fused deposition modeling (FDM), is an advanced 3D shaping technology, employing a layer‐by‐layer process to construct 3D objects. However, the weak interlayer bonding restricts the performance and functionality of FDM‐fabricated parts. Herein, boronate bond exchange is utilized to enhance interlayer mechanical strength and enable modular 4D printing of polylactic acid (PLA). Blending the dynamic system endows PLA with improved interlayer adhesion and welding capabilities. The blended filaments demonstrate excellent printability, with a 150% enhancement in Z‐axis interlayer strength, while nearly unchanged along the X‐axis. Moreover, this enhanced interlayer bonding facilitates the modular assembly of intricate structures, eliminating the need for traditional 3D‐printed supports. Combined with shape memory effects, diverse modular 4D printing possibilities are demonstrated. This strategy highlights the potential of dynamic covalent bonds in 3D printing, enhancing not only material performance but also intelligent designs.