Professor Thomas P. Russell, polymer science and engineering, was recently honored by the Neutron Scattering Society of America with its highest honor, the Clifford G. Shull Prize in Neutron Science, for “his pivotal role in the application of neutron reflectivity and small-angle neutron scattering to polymer science and his important work on behalf of the neutron scattering community.”
The prize is named in honor of Shull, who received the Nobel Prize in 1994 with Bert Brockhouse for seminal developments in the field of neutron science.
Russell says, “I was truly honored with this recognition and was happy to have been able to have made a significant contribution to the field that has advanced our understanding of long-chain molecules in thin film and at surfaces and interfaces. It was equally rewarding to have worked with outstanding scientists at Argonne National Laboratory (ANL) and the National Institute of Standards and Technology (NIST) and a talented group of post-doctoral fellows and graduate students.”
Scientists can measure the arrangement of polymers in a material and how they behave at a surface or interface by directing a neutron beam from a reactor or other source into the material, or bouncing the neutron off the surface and measuring how the scattered or reflected neutrons change with angle. Russell pioneered the use of neutron reflectivity and, with Gian Felcher at ANL and Charles Majkrzak and Sushil Satija at NIST, built the first neutron reflectometers. These instruments are now standard at every neutron source around the world, he notes. The technique produces information with unprecedented spatial resolution that cannot be obtained otherwise.
Specifically, Russell explains that neutrons have the ability to see individual polymer chains in bulk and in solution by substituting deuterium for hydrogen. Neutrons have “an incredible penetration power,” he adds, able to pass easily through thick glass or metals such as aluminum. The contrast between hydrogen and deuterium atoms – one of the largest between any atoms – “unlocks the power of neutrons to see a polymer chain.”
Russell has used neutron scattering and reflectivity to measure the characteristics of individual polymer chains in thin films and in spaces smaller than the size of the individual chains, which is important for the nanotechnological applications of polymers, he points out. He has investigated the inter-penetration of polymers at interfaces, a key to the adhesion between polymers and the strength of bonding between multilayers of polymers used in microelectronics.
Russell also uncovered the role of interfacial interactions in dictating the orientation of nanoscopic domains in thin films of block copolymers that has led to the development of ultra-low dielectric constant insulators for microelectronics, for storage devices with terabits of elements per square inch, for floating gate memory in microelectronics with exceptional longevity, filtration devices with pores tens of nanometers in size capable of separating virus particles, and for UV interference filters. He says that these techniques have had a great impact in polymer science and materials science in nanotechnology, memory devices, membranes and solar cells.
Russell will receive a plaque and a $5,000 honorarium at the annual American Conference on Neutron Scattering meeting in July, where he will also present an invited talk. The conference will be held online this year due to the COVID-19 pandemic.