Tube-based nanostructures are nanolattices made of connected tubes and exhibit nanoscale organization above the molecular level.

Lattices

Lattices are structures formed of arrays of uniformly sized cells. Ceramic lattice nanostructures have been formed using hollow tubes of

titanium nitride Titanium nitride (TiN; sometimes known as tinite) is an extremely hard ceramic material, often used as a physical vapor deposition (PVD) coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface prop ...

(TiN). Using vertex-connected, tessellated

octahedra In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

with 7-nm hollow struts with elliptical cross-sections and wall thickness of 75-nm produced approximately cubic cells 100-nm on a side at a scale of up to 1 cubic millimeter. The material's

relative density Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

was of the order of 0.013 (similar to

aerogel Aerogels are a class of manufacturing, synthetic porous ultralight material derived from a gel, in which the liquid component for the gel has been replaced with a gas, without significant collapse of the gel structure. The result is a solid wit ...

s). Compression experiments with multiple deformation cycles revealed

tensile strength Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate ...

s of 1.75

GPa Grading in education is the application of standardized measurements to evaluate different levels of student achievement in a course. Grades can be expressed as letters (usually A to F), as a range (for example, 1 to 6), percentages, or as num ...

without failure. The material was constructed from a digital design with direct laser writing onto a

photopolymer A photopolymer or light-activated resin is a polymer that changes its properties when exposed to light, often in the ultraviolet or visible region of the electromagnetic spectrum. These changes are often manifested structurally, for example harde ...

using 2-photon lithography followed by conformal deposition of TiN using

atomic layer deposition Atomic layer deposition (ALD) is a thin-film deposition technique based on the sequential use of a gas-phase chemical process; it is a subclass of chemical vapour deposition. The majority of ALD reactions use two chemicals called wiktionary:precu ...

and a final etching to remove the polymer. An earlier metallic tube lattice produced hollow tube nickel microlattices with a density of .9 milligram per cubic centimeter and complete recovery after compression exceeding 50% strain with energy absorption similar to

elastomer An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of ''ela ...

Young's modulus Young's modulus (or the Young modulus) is a mechanical property of solid materials that measures the tensile or compressive stiffness when the force is applied lengthwise. It is the modulus of elasticity for tension or axial compression. Youn ...

E scales with density as E ~ ρ2, in contrast to the E ~ ρ3 scaling observed for ultralight aerogels and

carbon nanotube A carbon nanotube (CNT) is a tube made of carbon with a diameter in the nanometre range ( nanoscale). They are one of the allotropes of carbon. Two broad classes of carbon nanotubes are recognized: * ''Single-walled carbon nanotubes'' (''S ...

nanofoam Nanofoams are a class of nanostructured, porous medium, porous materials (foams) containing a significant population of pores with diameters less than 100 nanometer, nm. Aerogels are one example of nanofoam. Metal Overview Metallic nanofoams ...

s with stochastic architecture. Hardness of 6 GPa and a modulus of 210 GPa were measured by nanoindentation and hollow tube compression experiments, respectively. These materials are fabricated by starting with a template formed by self-propagating photopolymer waveguide prototyping, coating the template by electroless nickel plating, and subsequently etching away the template.

Organic nanostructures

Nanostructured hollow multilayered tubes can be created by combining layer-by-layer (LbL) and template leaching. Such materials are of particular interest for tissue engineering since they allow the precise control of physical and biochemical cues of implantable devices. The tubes are based on

polyelectrolyte Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are t ...

multilayer films. The final tubular structures can be characterized by differential scanning calorimetry (DSC),

Fourier transform In mathematics, the Fourier transform (FT) is an integral transform that takes a function as input then outputs another function that describes the extent to which various frequencies are present in the original function. The output of the tr ...

infrared spectroscopy Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functio ...

(FTIR), microscopy, swelling and mechanical tests, including dynamic mechanical analysis (DMA) in physiological simulated conditions. More robust films could be produced via chemical cross-linking with

genipin Genipin is a chemical compound found in ''Genipa americana'' fruit extract. It is an aglycone derived from an iridoid glycoside called geniposide which is also present in fruit of ''Gardenia jasminoides''. Genipin is an excellent natural cross ...

. Water uptake decreases from about 390% to 110% after cross-linking. The cross-linked tubes are more suitable structures for cell

adhesion Adhesion is the tendency of dissimilar particles or interface (matter), surfaces to cling to one another. (Cohesion (chemistry), Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.) The ...

and spreading. Potential applications include

tissue engineering Tissue engineering is a biomedical engineering discipline that uses a combination of cells, engineering, materials methods, and suitable biochemical and physicochemical factors to restore, maintain, improve, or replace different types of biolo ...

References

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Lattices

Organic nanostructures

References

See also