Programmable Building Blocks via Internal Stress Engineering for 3D Collective Assembly

Abstract

The collective assembly of finite building blocks can induce complicated scaled-up architecture for structural diversity and multifunctionality. In this study, the concept of 2D to 3D shape morphing via frontal photopolymerization is employed for the rapid and repetitive fabrication of geometrically tailorable building blocks. The photoabsorber generates an internal stress gradient which induces a mismatch of volumetric shrinkage within a photocured monolithic 3D structure. The final 3D curvilinear architecture is investigated through systematic analysis by controlling the spatiotemporal conditions of 3D shape morphing. The spatiotemporal effect consists of pre/postcuring methods and geometry of the 2D patterns inspired by fractal elements including even/odd condition, spirality, and self-similarity. Finally, the concept of collective assembly is introduced to construct multiple objective architectures. Each morphed structure contributes to the assembly of hierarchical 3D structures as a building block. Inspired by famous architectures, the collective hierarchical 3D structures are demonstrated by replicating the form of certain landmarks. In addition, scaled-up assembled 3D structure can withstand 150 times of its own weight and can be applied for the frame of electronic devices. The collective assembly of programmable building blocks has the potential for various versatile applications in rapid prototypes of optical metamaterials, antennas, and curved electronic devices.