Much of the excitement in the rapidly emerging field of nanotechnology is over new and increasingly versatile, yet ultra-thin coatings applied to electrical components such as computer chips, machine parts, and optical devices ranging from camera lenses to chic eyewear.

A specialty of MARTECH scientists is the design and fabrication of such thin films for various materials. Some of the techniques used involve the latest tools in the trade, an array of high-performance gadgets that vaporize matter in laying down thicknesses of only a few atoms over wafers made of metal or silicon. Typically, these vapor-deposition techniques are what industry uses to build computer chips. Thin films can be (and usually are) laid down on a chip's surface in layers, each with a different electrical property.

But outside the computer-chip business, decidedly less high-tech methods still command great interest because they're comparatively easy to do, are extremely adaptable to project requirements, and also because they're inexpensive. Products range from improved optical devices to tiny insulators used in the microelectronics industry.

Two MARTECH chemists, Joseph Schlenoff and Alan Stiegman, have developed novel ways of making durable thin films of ultra-high quality in the confines of their wet-chemistry labs. Schlenoff spins two different kinds of polymers onto the surface of silicon wafers. Each layer is charged, one negative, one positive, and laid down in alternating fashion. Thicknesses of his coatings range from 10 nanometers (10 billionths of a meter) to 10,000 nanometers, or one micron.

He's automated the process with a one-of-a-kind robotic device built by the chemistry department's machine shop. Affectionately named "Delphine," after a long-departed grad student whose duty it was to build each wafer by hand, the device can churn out as many perfect coatings as needed in short order.

Stiegman's work exploits the curious properties of a class of materials collectively called xerogels, which are basically glasses that he makes from scratch in his lab. Made entirely of silica, the glasses have surfaces full of nano-sized (and smaller) holes. Stiegman spin-coats the porous surface with a mixture of inorganic chemicals that permeate all the holes and bond to the surface. Then the coated xerogels are subjected to a process called photolysis, whereby light is used to set off a chemical reaction that turns the coating into a slick polymer.

One coating scheme Stiegman stumbled onto, a synthesis using vinyl fluorine gas with vanadium as a catalyst, shows promise for the market. Testing has shown that his glasses coated with polydifluoroethylene, or PVF2, exhibit an ultra-slick, durable surface that beads up water as dramatically, if not more so, than Teflon or other popular commercial coatings found today on everything from cookware to dental tools. – F.S.