Nanocomposites in optics

Plastics Engineering, May, 2007 by Roger Corneliussen

U.S. Patent 7,183,337 (February 27, 2007), "Optically Clear Nanocomposites and Products Using Nanoscale Fillers," Tapesh Yadav and Clayton Kostelecky (NanoProducts Corp., Longmont, Colorado, USA).

A nanostructured powder is one having a domain size less than 100 nm, typically 50 nm or smaller. The number of atoms in this nanofiller is on the order of the number of atoms in a polymer chain. Thus, a nanocomposite can have a very high number density. In addition, because of their small size, the fillers may have properties that are different from those of larger particles. An important characteristic of optical material is its refractive index, as well as its transmission and reflective characteristics. Nanostructured fillers can be used to produce composites with refractive indices engineered for a particular application, such as gradient lenses. Gradient lenses reduce the need for polishing. The use of nanostructured fillers may also help filter specific wavelengths. Another advantage in optical applications is enhanced transparency because of the small filler size, which is much less than the wavelength of visible light. Examples include 20-vol% indium tin oxide in PMMA, 20- to 80-vol% hafnium carbide fillers in PMMA, and 15- and 20-vol% copper in PMMA and PVA. These nanocomposites were used to form varistors, thermal battery electrodes, and magnetic inductors.