Christopher Spadaccini¹; ¹Lawrence Livermore National Laboratory

We are combining advanced design methods such as topology optimization, with advanced additive micro- and nanomanufacturing techniques to create new material systems with previously unachievable property combinations – mechanical metamaterials. The performance of these materials is fundamentally controlled by geometry at multiple length-scales rather than chemical composition alone. We have demonstrated designer properties of these mechanical metamaterials in polymers, metals, ceramics and combinations thereof. Properties include ultra-stiff lightweight materials, negative stiffness, and negative thermal expansion to name a few, as well as functional properties such electrical, optical, acoustic, and chemical responses. We have primarily utilized our custom developed additive manufacturing techniques to create these structures and materials. These include projection microstereolithography (PuSL), direct ink writing (DIW), electrophoretic deposition (EPD), volumetric AM (VAM) via tomographic reconstruction (VAM), parallel two-photon polymerization, and diode-based additive manufacturing (DiAM) of metals. We will also review design and synthesis of the feedstock materials themselves.