Nanocomposites

Nanoparticles are ubiquitous in today’s world. Nanotechnology is the manipulation of matter on a molecular level. Recall that a carbon-carbon bond length is ~0.1 nanometer (nm), a double helix strand of DNA is 2nm, and the average human hair is 50,000nm in diameter. Nanostructured materials are not new, but significant innovations have been developed here at NanoSonic.

Over the past several decades, NanoSonic has optimized multiple nanotechnology manufacturing methods that result in multifunctional materials that could not be generated in any other way. For example, NanoSonic’s patented self-assembly technique is a powerful new tool used for creating nanocomposites with multiple, controlled, constitutive properties. When a material exhibits more than one function, it is known as multifunctional. Materials that perform two or more functionalities translate into significant weight savings. Representative examples of NanoSonic’s synergistic family of materials are Metal Rubber™, HybridSil™ and HybridShield™.

Metal Rubber nanocomposites are highly electrically conductive, optically transparent, and exhibit thermomechanical durability beyond what is possible from traditionally formed nanocomposites. Unlike metals, Metal Rubber can be stretched repeatedly to greater than 1000 percent elongation without loss of electrical conductivity or rupture. The mechanical modulus can be tailored and can be based on thermoplastics, thermosets, or shape memory polymers as NanoSonic synthesizes the high performance polymer matrix resins with chemical sidechain functionality tailored for our nanoparticles (Shape Memory-Metal Rubber morphing wings).

The Metal Rubber family of materials is not limited to “stretchable metals”, as we also synthesize our nanoparticles in-house. The smart functionality, or metal in metal rubber, can be altered via different materials. Our nanoparticles include but are not limited to metals, ceramics, magnetics, oxides, quantum dots, mixed metal oxides, and core-shell hybrid particles.

Military grade HybridSil and commercial grade HybridShield nanocomposites are a family of nanocomposites based on siloxanes. Siloxanes are polymers based on silicon-oxygen repeat units. Silicon atoms are larger than carbon and allow for a wider angle of bond rotation, hence greater flexibility. Our family of HybridSil and HybridShield products are currently under production. NanoSonic’s commercial grade HybridShield was applied to half of a duplex for testing; the half of the duplex that was not treated was engulfed in flames within 15 min. The HybridShield treated roof was completely intact the day after the fire.

Basics of Nanomaterials and Nanocomposites
Nanomaterials are tiny, microscopic materials with at least one dimension that is less than 100 nanometers (nm). A nanometer is one-billionth of a meter – and a meter is about 39 inches long. One human hair is about 100,000 nanometers wide.

If a nanomaterial is formed into a one-dimensional layer, it is called thin-film or surface coating. If a nanomaterial is less than 100nm in two directions and extended into one direction, it is called a nanowire or nanotube. A nanomaterial that is nanoscale in three dimensions is called a nanoparticle.

Nanocomposites are materials that incorporate nanosized particles into a matrix of standard material. The addition of nanoparticles results in an improvement in properties that can include mechanical strength, toughness, impermeability, optical clarity and electrical or thermal conductivity. In nanocomposites, the nanoparticles (clay, metal, carbon nanotubes) act as fillers in a matrix, usually polymer matrix.

Two principal factors cause the properties of nanomaterials to differ significantly from other materials: increased relative surface area, and quantum effects. These factors can change or enhance properties such as reactivity, strength and electrical characteristics. As a particle decreases in size, a greater proportion of atoms are found at the surface compared to those inside the particle; they have an extremely high surface-to-volume ratio.

To understand the effect of particle size on surface area, consider a U.S. silver dollar. One silver dollar contains 26.96 grams of coin silver, has a diameter of about 40 mm, and has a total surface area of approximately 27.70 square centimeters. If the same amount of coin silver were divided into tiny particles — say one nanometer (nm) in diameter — the total surface area of those particles would be 11,400 square meters, which is equal to 122,708 square feet, or 2.817 acres – this new surface area of the particles is 4.115 million times greater than the surface area of the silver dollar! So you see, the smaller the particles and the more of them, the greater the particle surface area. SOURCE

Materials on this tiny scale will be the same material but with different behaviors or properties. One way to understand how the properties of a single material can change based on size is to consider a cup of coffee; if you pour hot water over whole coffee beans, you might get a slightly brownish liquid with very little flavor; now, if you grind the beans into fine particles and then pour hot water over them, a highly flavored and scented liquid emerges that is unlike the whole-bean liquid.

The other primary property of nanomaterials – quantum effects – can change the optical, electrical and magnetic behavior of materials, particularly as the structure or particle size approaches the smaller end of the nanoscale. A substance that is normally opaque, such as copper, can become transparent at nanoscale; aluminum is stable in the big world, but at nanoscale it becomes combustible; gold is chemically inert and solid at normal scales, but turns into a liquid that can be used as a chemical catalyst at nanoscales at room temperature; and as seen in thin-film solar cells, a good insulator such as silicon becomes a great conductor at nanoscale.

Nanocomposites

ESA Process Video Animation

Nanomaterials