At the truly tiny scale of nanoparticles, attractions and repulsions among atoms and molecules often overwhelm the more ordinary forces at play in the larger-scale world.
Such nanoscale forces, driven in some cases by the momentary orientations of electrons, become a problem when the goal is to keep particles evenly dispersed in liquid — a challenge for manufacturers who want to make products featuring nanoparticle-enhanced films or coatings. Nanoparticles suspended in solvents at high densities tend to clump while the coating is drying, negating the benefits of their nanosized ingredients.
Improving the processing and manufacturability of such coatings and thin films is the primary goal of a research collaboration that began last spring among Sandia and a half dozen major companies.
The Nanoparticle Flow Consortium includes 3M, BASF, and Corning, among others. Sandia serves as the hub for the three-year, $2 million cooperative research and development agreement.
From lab to plant
Currently most nanoscience takes place in labs where very small amounts of matter are manipulated using specialized equipment. To manufacture consumer products, companies will need to master high-throughput, large-scale nanomaterial processing techniques, says Randy Schunk of Nanoscale & Reactive Processes Dept. 1516, who leads Sandia’s portion of the work.
“Manufacturable implies practical,” he says. “Companies need to disperse these particles in liquid, then cast them, coat them, layer them, or paint them on something, often over large areas. Such problems aren’t necessarily going to be addressed in a research lab.”
The potential benefits are enormous, he says. The National Science Foundation estimates that by 2015 the worldwide nanotechnology market could reach a trillion dollars annually. “The amount of money involved is staggering,” says Randy.
Already today’s flat-screen TVs incorporate nanofilms in their display screens. On the horizon are stronger and more transparent glues, lightweight composites, sealants for microelectronics devices, and new materials for sensing and medical devices.
Possible future products include coatings that react to the environment, paint or glass that color-shifts like a chameleon, self-lubricating or self-healing surfaces, or antimicrobial coatings for hospital ventilation systems, for example.
Toward a predictive capability
The consortium’s work will address two main technical challenges: stable dispersal of nanoparticles in solution during processing, and improved understanding of particles dispersed in materials under stress or flow and how these states are affected by nanoscale forces. Both were viewed by participants as limiting factors in bulk manufacturing of nanomaterials and thin films.
Sandia is developing the modeling and simulation tools needed to understand liquid flow chemistry, nanoparticle dispersal stability, and particle control. Together with Sandia’s high-performance computers, says Randy, the tools are expected to result in a predictive capability for nanoparticle processing — meaning materials and techniques with the highest chances of success can be designed on computers before they are ever tried in a laboratory. The modeling tools will be available to all consortium partners.
Resolution of these technical barriers may open doors not only to advanced coatings, but to layered bulk materials as well, he says.
Within Sandia the work is a Labs-wide collaboration, with contributing scientists and engineers from four centers, says Randy. They include Steve Plimpton (1416), Mike Brown (1412), Gary Grest, Matt Lane, Matt Petersen (all 1114), Nelson Bell (1816), Jeremy Lechman (1516), and Anne Grillet (1513).
Work benefits NINE
Nanoparticle dispersal in liquid is a key issue for the companies involved in the National Institute for Nano Engineering (NINE), a national hub for nanoscale engineering and education. NINE funds Sandia’s portion of the consortium’s work, and NINE collaborators and students will benefit, he says.
The Nanoparticle Flow Consortium is modeled after a similar cooperative research effort that began at Sandia in 1996, the Coating Related Manufacturing Processing Consortium (CRMPC). The CRMPC included many of the same partners and resulted in a software package, GOMA 5.0, which far exceeded existing modeling capabilities for coating processes, Randy says.