New Technology Ventures

Nanotechnology: At the Level of Atoms

Nanotechnology:The creation and utilization of materials, devices, and systems through the control of matter on the nanometer-length scale – that is, at the level of atoms, molecules, and supramolecular structures (according to the National Science and Technology Council Committee on Technology Interagency Working Group on Nanoscience, Engineering, and Technolog, 2000).

Dow Corning had a heavy stake in the nanotechnology of materials and systems even before the term was invented. For instance, a long-used nanomaterial is silica. Silica is used in poly(dimethylsiloxane) – or PDMS – elastomers as a very effective network reinforcement – indeed, silicone rubbers are seriously limited without such reinforcement.

Silicone Surfactant Systems
More recently, many nanotechnology examples can be found in Dow Corning’s silicone surfactant systems. Depending upon the choice of building units and the engineering strategies, controlled structures can readily be formed in the several-hundred-nanometer range.

For instance, silicone-poly(oxoethylene) copolymers form vesicles, which can function not only as encapsulants and delivery agents of active ingredients but also as nanoreactors. Microemulsions and liquid crystals formed from silicone surfactants have been used to enhance delivery of personal care products and to direct synthesis through templating of mesostructured materials. And silicone-organic copolymers self-assemble to ordered or disordered phases, which control the physical and mechanical properties of the polymeric system and facilitate the stabilization of multiphase-component emulsions.

Toughening Silicone Resins One contemporary nanotechnology example can be found in the toughening of silicone resins. Significant improvements in the fracture toughness and fracture energy properties of resins were achieved via the in situ formation of nanosized, second-phase, PDMS-rich particles, which were securely adhered to the matrix. This advancement allowed Dow Corning to position these brittle, “glassy” polymers in parity with organic thermoset systems (such as epoxies). This was done while maintaining all of the other positive attributes of silicones. With this discovery, Dow Corning has found opportunities for new material forms (such as films and composites), for new uses, and – more important – for the design of new classes of siloxane polymers. In 2002, Dow Corning brought the first toughened silicone resin system to a receptive market.		Toughened silicone resin composite.
Liquid Crystalline Materials Another current example of Dow Corning nanotechnology in action is the development of our thermotropic oligosiloxane liquid crystalline (LC) materials. Oligosiloxane functionalization can be used to tune the properties of mesogens. This tuning can include: • Broadening the temperature range over which the LC phase exists • Changing the observed LC phase • Altering the miscibility of dopant molecules (“guests”) in a LC “host” • Controlling the tilt angle of chiral mesogens within layers of the organized system		Micrograph of Smectic A Phase
The oligosiloxane component tends to induce microphase segregation, thus ordered phases (such as lamellar structures) are readily observed. This technology provides a strong platform for Dow Corning in the liquid crystal display market (laptop computers, PDAs, and mobile phones, for example) and in other electro-optics opportunities.		Micrograph of Chiral Smectic C Phase.

The Future of Nanotechnology
The strengths of Dow Corning’s science and nanotechnology are leading to new, high-performance, silicon-based products and technologies that were not possible before. Our current activities systematically address, manipulate, organize, and control matter on the nanometer-length scale. Through nanometer-scale structures, we make it possible to control fundamental properties of materials, such as their melting temperature, magnetic properties, charge capacity, mechanical properties, and even color – without changing the materials’ chemical composition.

Silicon-based nanomaterials have potential as the “material of choice” for numerous applications in photonics, electronics, energy, and biology. With our investment in understanding, manufacturing, and developing silicon-based materials, Dow Corning is in a powerful position to continue to make tomorrow’s discoveries and lead the way in new and exciting opportunities in nanotechnology.

Learn more about some of Dow Corning’s other new technology ventures, including:

• Plasma

Sources:

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