When you combine inorganic materials with organic particles, especially very small particles called nanoparticles, you often get materials with interesting characteristics.  Nanoparticle films are one such material, consisting of a thin network of inorganic materials with nanoparticle bound to it.  Scientists have cooked up many creative uses for the films, from electronics to drug delivery.

However, previous methods used to manufacture the films -- polymer encapsulation of the nanoparticles or the use of nanoglue ("cross-linkers") -- were expensive and yielded fragile films.  Thus it is exciting that researchers at Vanderbilt University have discovered a cheaper way to create hardier nanofilms.

The new method uses a modified form of electrophoretic deposition (EPD), a process used to paint metal parts such as automobile bodies, prosthetic devices, appliances and beverage containers.  The new method adds a polymer layer to the electrode, which organizes the nanoparticles as they are deposited.  After the coating is done, the polymer is dissolved, freeing the film. 

The resulting film is strong enough to be rubbed against surfaces with a pair of tweezers without dissolving.  This level of abuse would have quickly destroyed previous films.  The researchers made films out of two kinds of nanoparticles -- iron oxide and cadmium selenide -- but believe that many other kinds can be used as well.  States James Dickerson, assistant professor of physics at Vanderbilt, "The technique is liberating because you can make these films from the materials you want and use them where you want."

An early target for the new films is to use them to replace the hafnium oxide "high-k" dielectric materials used to prevent current leakage in increasingly tiny transistors found in processors.  Describes Professor Dickerson, "We have made high-k nanoparticle films that could be cheaper and more effective than the high-k materials the manufacturers are currently using."

The deposition process could also be used to make flexible-film computer or TV screens.  Repeated flexing of the current thin films leads to no signs of cracking, raising their promise for these kinds of applications.

The new research was published late last month in the journal Chemical Communications.