A nanolattice is a synthetic porous material consisting of nanometer-size members patterned into an ordered lattice structure, like a space frame. The nanolattice is a newly emerged material class that has been rapidly developed over the last decade. Nanolattices redefine the limits of the material property space. Despite being composed of 50-99% of air, nanolattices are very mechanically robust because they take advantage of size-dependent properties that we generally see in nanoparticles, nanowires, and thin films. The most typical mechanical properties of nanolattices include ultrahigh strength, damage tolerance, and high stiffness. Thus, nanolattices have a wide range of applications. Driven by the evolution of

3D printing 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

techniques, nanolattices aiming to exploit beneficial material size effects through miniaturized lattice designs were first developed in the mid-2010s,. Nanolattices are the smallest man-made lattice

truss A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembl ...

structures and a class of

metamaterials A metamaterial (from the Greek word μετά ''meta'', meaning "beyond" or "after", and the Latin word ''materia'', meaning "matter" or "material") is any material engineered to have a property that is not found in naturally occurring materials. ...

that derive their properties from both their geometry (general metamaterial definition) and the small size of their elements. Therefore, they can possess effective properties not found in nature, and that may not be achieved with larger-scale lattices of the same geometry.

Synthesis

To produce nanolattice materials,

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

templates are manufactured by high-resolution 3D printing processes, such as multiphoton lithography,

self-assembly Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. When the ...

, self-propagating photopolymer waveguides, and direct laser writing techniques. Those methods can synthesize the structure with a unit cell size down to the order of 50 nanometers. Genetic engineering also has the potential in synthesizing nanolattice.

Ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

nanolattices are formed by post-treatment of the polymer templates with techniques including

pyrolysis The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...

, atomic layer deposition, electroplating and

electroless plating Electroless plating, also known as chemical plating or autocatalytic plating, is a class of industrial chemical processes that create metal coatings on various materials by autocatalytic chemical reduction of metal cations in a liquid bath. This ...

. Pyrolysis, which additionally shrinks the lattices by up to 90%, creates the smallest-size structures, whereby the polymeric template material transforms into carbon, or other ceramics and metals, through thermal decomposition in inert atmosphere or vacuum.

Properties

At the nanoscale, size effects and different dimensional constraints, like grain boundaries, dislocations, and distribution of voids, can tremendously change the properties of a material. Nanolattices possess unparalleled mechanical properties. Nanolattices are the strongest existing cellular materials despite being extremely light-weight. Though consisting of 50%-99% air, nanolattice can be as strong as steel. Its effective strength can reach up to 1 GPa. On the order of 50nm, the extremely small volume of their individual members, such as walls, nodes, and trusses, thereby statistically nearly eliminates the material flaw population and the base material of nanolattices can reach mechanical strengths on the order of the theoretical strength of an ideal, perfect crystal. While such effects are typically limited to individual, geometrically primitive structures like

nanowires A nanowire is a nanostructure in the form of a wire with the diameter of the order of a nanometre (10−9 metres). More generally, nanowires can be defined as structures that have a thickness or diameter constrained to tens of nanometers or less ...

, the specific architecture allows nanolattices to exploit them in complex, three-dimensional structures of notably larger overall size. Nanolattices can be designed highly deformable and recoverable, even with ceramic base materials. Nanolattices are able to undergo 80% compressive strain without catastrophic failure and then still recover to 100% original shape. Nanolattices can possess mechanical metamaterial properties like auxetic (negative Poisson's ratio) or meta-fluidic behavior (large Bulk modulus). Nanolattices can combine mechanical resilience and ultra-low

thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

and can have electromagnetic metamaterial characteristics like optical cloaking. However, one of the challenges in nanolattices research is figure how to retain the robust properties while scaling up. It is inherently difficult to keep nanoscale size effects in bulk structure. The straightforward workaround to overcome this challenge is to combine bulk processes with thin film deposition techniques to retain the frame space hollow structure.

Application

The first market for nanolattices may be small-scale, small-lot components for biomedical, electrochemical, microfluidic, and aerospace applications, which require highly customizable and extreme combinations of properties. In the aerospace industry, the application of nanolattice could make the aircraft lighter and save lots of energy.

References

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Synthesis

Properties

Application

See also

References