Modular 4D Printing via Interfacial Welding of Digital Light-Controllable Dynamic Covalent Polymer Networks

Summary Advanced multifunctional devices increasingly rely on challenging complex shapes for their functions. 3D printing offers a solution but is often limited by the fabrication speed and/or material diversity. 4D printing based on digitally controlled 2D-to-3D transformation is advantageous in speed, but the accessible shapes are limited and integration of multiple materials is difficult. We report herein a concept that significantly extends the technological scope by combining 4D printing with modular assembly. Specifically, 4D photo-printed structures based on dynamically crosslinked polymers can be assembled in a modular fashion by interfacial bond exchange. Complex 3D objects with tailorable multiple materials can consequently be produced. This allows the fabrication of sophisticated shape-memory devices including a 3D Miura-patterned structure with zero Poisson's ratio and a Kresling-patterned cylindrical structure with superior mechanical stability. Our approach extends the possibilities for the future development of multifunctional devices with seamless integration of material, structure, and function.