Advances in 3D/4D printing of mechanical metamaterials: From manufacturing to applications

Advanced Fabrication of Mechanical Metamaterials Based on Micro/Nanoscale Technology

“…4D printing offers an efficient approach to dynamically and precisely modifying the structure and functionality of mechanical metamaterials post‐manufacturing, providing intelligent adaptability and greatly enhanced design flexibility. [ 95 ] Limited by available materials and manufacturing technologies, the research results of active mechanical metamaterials via 4D printing are mainly characterized by mesoscale (i.e., from a few millimeters to tens of centimeters), single response, and mono‐function.…”

“…In addition to the 3D structure in space, the development of active materials enables mechanical metamaterials to interact with external environmental conditions, such as heat, light, electricity, and magnetism, and realize dimensional switching from 2D to 3D, which is also called 4D metamaterials. [94,95] The scalability of mechanical metamaterials provides a significant advantage, making them useful in a range of fields, including aerospace and biomedical scaffolds. It should be noted that multidimensional and micro/nanoscale characteristics can significantly improve the mechanical performance of mechanical metamaterials, but at the same time, it also poses unprecedented challenges to manufacturing technology.…”

4D Printing of Chiral Mechanical Metamaterials with Modular Programmability using Shape Memory Polymer

“…Following this route, a variety of mechanical metamaterials have been explored in terms of dimension raising (from 2D to 3D, 3D to 4D), reconfigurability, and multifunctionality. [ 32–34 ] Shape memory polymers (SMPs) are a class of smart polymer materials that can actively deform under external stimuli. Unlike general elastomers that deform after loading and recover immediately after unloading, SMP can maintain a temporary shape when the load is removed and return to the original shape under a certain stimulus, providing a convenient self‐locking mechanism for mechanical metamaterials.…”

Additive Manufacturing of Elastomeric Composite Lattices with Thermally Grown Micro‐Architectures for Versatile Applications

“…To date, many manufacturing technologies including freeze casting, [11,12] photopolymer prototyping, [13] moldings, [14] and additive manufacturing (i.e., 3D printing) [15] have been employed in constructing different microstructured materials, and different types of microstructured materials have been unveiled in recent years. [16,17] Among those manufacturing methods, 3D printing has disruptive manufacturing characteristics such as manufacturing arbitrarily complex and variable geometric architectures, personalization, and rapid prototyping, and thus has been increasingly adopted for fabricating complex microstructured materials, which is difficult to achieve by conventional manufacturing methods, and it provides a broader design space for micro-structural materials. [18][19][20][21][22][23] For instance, Studart et al fabricated a recyclable and lightweight liquid-crystal-polymer structure with hierarchical architectures, complex geometries and unprecedented stiffness and toughness via fused deposition 3D printing method.…”

“…Generally, it is difficult to regulate the internal microstructures using raw materials as printing inks. [17,22] Besides, the current 3D printed microstructured material workpieces always suffer from inherent shortcomings such as fixed morphological features (including micro-and macro-scale) after manufacturing, which greatly limits the development of micro-structural material with versatile functionalities. [8,17,26,34] Overall, the physical realization of microstructured materials with complex morphologies and secondary (or internal) micro-architectures requires a series of innovative manufacturing technologies with new materials recipe.…”