Disordered Spinodal Metamaterials—Curvature-Guided Properties and Scalable Self-Architecture

Additively manufactured (AM) architected materials have revolutionized the design of mechanical systems by achieving exceptional mechanical properties, particularly through periodic, ordered truss-based lattices known for their high stiffness- and strength-to-weight ratios. However, these lattices often suffer from bending-dominated responses and stress concentrations at sharp joints, which can initiate and propagate failure. Additionally, their reliance on symmetry and periodicity makes them susceptible to defects arising from AM processes, significantly reducing performance. While high-resolution AM techniques could address these defects, they tend to be either low-throughput or prohibitively expensive, limiting scalability. Spinodal metamaterials offer a promising alternative, as their smooth, bicontinuous morphologies and non-periodic structures inherently avoid stress concentrations and are less sensitive to defects. Their design also allows for scalable, self-assembly manufacturing pathways beyond AM. Furthermore, spinodal metamaterials exhibit tunable mechanical properties that can be modified by controlling the distribution of curvature within the materials. This control over curvature enables the design of anisotropic mechanical behavior, which can be tailored for specific applications. Uncovering the complex structure-property relations of spinodal metamaterials will help guide the design of next-generation materials that combine order and disorder.
In this study, we explore the influence of curvature and anisotropy on the mechanics of spinodal metamaterials and present new, scalable fabrication techniques. Using computational methods, we generate spinodal morphologies that mimic the physics of fabrication, and we introduce tunable anisotropy by penalizing specific interface directions. This results in curvature distributions that are dependent on the chosen directions. We fabricate prototypes using two-photon lithography and test them via in situ nanomechanical compression experiments, assessing the impact of curvature on stiffness, strength, and toughness. These experiments are complemented by finite element analysis (FEA) and theoretical models, revealing the relations between disordered curvature distribution, stress distribution, and mechanical performance. We develop new geometric metrics to quantify anisotropic stiffness, strength, and toughness, which enable the optimization of curvature distribution to tailor mechanical properties. Additionally, we investigate the fabrication of spinodal morphologies through natural spinodal decomposition processes. Parametric studies, supported by scanning electron microscopy (SEM) and X-ray computed tomography (XCT), provide insights into structure formation and process-structure relations. Micro-scale X-ray tomography is used to digitally reconstruct the internal structures for further analysis through theoretical modeling and FEA. To enable scalable fabrication, we apply nanofabrication techniques to conformally coat these spinodal morphologies with nanoscale ceramic and metallic films, resulting in self-architected spinodal shells.
This work highlights the potential of spinodal metamaterials as a scalable solution for achieving high-performance, defect-tolerant materials with tunable mechanical properties, expanding the design space for architected materials in a wide range of applications.