CHESS DMR-0936384 2013

Versatile polymer film synthesis method inventedJoel Brock, Cornell University, DMR 0936384

Pliable scaffolds with structural hierarchy can be synthesized using long-chain block copolymers (right, inset).

H. Sai, K. W. Tan, K. Hur, E. Asenath-Smith, R. Hovden, Y. Jiang, M. Riccio, D. A. Muller, V. Elser, L. A. Estroff, S.M. Gruner, U. Wiesner, “Hierarchical Porous Polymer Scaffolds from Block Copolymers,” Science 341, 6145, pp. 530-534, 2013

Intellectual Merit: Creatively combining established techniques, Cornell researchers have devised a synthesis method for hierarchical porous polymer films that may help make these materials useful for applications ranging from catalysis to bioengineering. Graduate student Hiroaki Sai, first author on a paper reporting the results online in the journal Science, collaborated with Cornell scientists across disciplines both to both growth and characterize the materials using the CHESS G1 station. The hierarchically structured polymers are porous at both micron and nanometer length scales, providing both high flux, which means that material can flow through the porous structure efficiently, and high surface area. Both are important, for example, in rapid catalytic conversions. The porous materials were self-assembled from a series of block copolymers, which are large molecules comprising “blocks” of repeating units.

CHESS DMR-0936384 2013

Schematic for the synthesis method and ternary phase diagram. Synthesis of hierarchically porous polymer scaffolds with ordered mesostructure using the SIM2PLE method.

H. Sai, K. W. Tan, K. Hur, E. Asenath-Smith, R. Hovden, Y. Jiang, M. Riccio, D. A. Muller, V. Elser, L. A. Estroff, S.M. Gruner, U. Wiesner, “Hierarchical Porous Polymer Scaffolds from Block Copolymers,” Science 341, 6145, pp. 530-534, 2013

Broader Impacts: For engineering and technology applications, forming perfect porous polymer films is not enough. Films need both large and small pores and the process of making them needs to be simple, versatile and repeatable. Cornell researchers have developed a new method for synthesizing dual porosity by mixing two components from two coexisting phases, like water and oil, separated by tens of microns with a continuous interface between them. When one additive was washed away, e.g., with water, what remained was a continuous pattern of porosities on two length scales – tens of microns and tens of nanometers. “It’s about as simple as it gets,” lead researcher Uli Wiesner said. The researchers used various diblock and even triblock polymers and believe that the method can be generalized to form many versions of this highly sought-after material.

Versatile polymer film synthesis method inventedJoel Brock, Cornell University, DMR 0936384

CHESS DMR-0936384 2013

Scientists speed up search for new materialsJoel Brock, Cornell University, DMR-0936384

The metallization of the PnSC device is shown along with the detailed view of a single serpentine sensor that provides uniform sample heating over a broad range of scanning rates. The footprint of the x-ray beam is highlighted in green at center.

J. M. Gregoire, K. Xiao, P. J. McCluskey, D. Dale, G.Cuddalorepatta, and J. J. Vlassak. "In-situ X-ray diffraction combined with scanning AC nanocalorimetry applied to a Fe0.84Ni0.16 thin-film sample," Applied Physics Letters 102, 201902-4, 2013.

Intellectual Merit: Many new materials need to be heated or cooled, sometimes very rapidly, in order to transform them into useful products. In a recent paper in Applied Physics Letters, lead author John Gregoire describes a special x-ray apparatus used at the CHESS A2 station to capture the thermal and structural details of the transformation behavior of an important iron-nickel alloy during rapid heating and cooling. The combination of parallel nano-scanning calorimetry (PnSC), which heats and cools a small specimen area rapidly, with in-situ x-ray diffraction measurements opens up the possibility of simultaneously capturing information about both the thermal and the structural properties of materials far from equilibrium. PnSC analyzes thermal properties by quickly sweeping temperature at rates up to 100,000 C degrees per second. In situ x-ray measurements provide additional information required for a more complete understanding of materials reactions

CHESS DMR-0936384 2013

Schematic of the nanocalorimetry and x-ray experiment showing the path of the 30 keV synchrotron beam through the vacuum chamber and nanocalorimeter device. The device can be seen through the polyimide window and the detector region is represented by a measured diffraction image.

J. M. Gregoire, K. Xiao, P. J. McCluskey, D. Dale, G.Cuddalorepatta, and J. J. Vlassak. "In-situ X-ray diffraction combined with scanning AC nanocalorimetry applied to a Fe0.84Ni0.16 thin-film sample," Applied Physics Letters 102, 201902-4, 2013.

Broader Impacts: Discovering new materials often involves searching through hundreds, thousands, or millions of compounds to find exciting new possibilities. Complicating this search further, many new materials need to be heated or cooled in order to transform them into useful products. Researchers anticipate their new technique for rapid heating and cooling coupled with time-resolved in situ x-ray diffraction could study reactions of solid materials surrounded by gaseous atmospheres. Such studies would help develop high-temperature oxidation resistant materials - that is, materials that don't rust. Other applications might include materials that efficiently utilize water as a thermochemical fuel, which could lead to hydrogen fuel cells capable of powering small to large scale machinery like cell phones to automobiles.

Scientists speed up search for new materialsJoel Brock, Cornell University, DMR-0936384