UW MRSEC Highlights

Professional Development, Research, and Community Building: The Wisconsin REU Programs

Mon, 17 Aug 2009 13:01:40 -0500

UW MRSEC director Juan de Pablo learns about a students research during the Nano REU poster session.

The University of Wisconsin-Madison MRSEC offers an inclusive, welcoming research and professional development opportunity to underrepresented students every summer through its two Research Experiences for Undergraduate (REU) programs. The MRSECs Nano REU program, led in collaboration with the UW Nanoscale Science and Engineering Center (NSEC) and the UW Graduate School, hosted 12 students in summer 2009 as they engaged in research, learned about effective poster presentations and the grad....

K-6 Science Outreach: MicroExplorers

Mon, 16 Mar 2009 16:10:09 -0500

Troy Dassler (MRSEC RET Fellow; 1st grade teacher), Douglas B. Weibel (DMR #0520527) We are developing a discovery-based science program for K-6 students based on digital microscopy. The program is MicroExplorers (www.MicroExplorers.org).We have developed a range of different science outreach materials that span the fields of materials, chemistry, biology, and engineering that engage students and promote family-based learning.Through events on campus, the Childrens Museum in....

Curvature-Induced Lipid Localization as a New Approach to Dynamic Materials

Mon, 16 Mar 2009 16:03:17 -0500

Abishek Muralimohan, Douglas B. Weibel (DMR #0520527)[Image391]We are studying the role of curvature-induced lipid localization in bacterial cell membranes as a mechanism of controlling proteins at interfaces.We have developed a technique for controlling bacterial cell curvature by growing cells in microchannels embossed in hydrogels. Using these materials we are measuring the curvature for spontaneous localization of cardiolipin in the cell membrane.Our goal is to initially....

Mechanical Damping, Negative Poissons Ratio and Softening of the Compressibility of Barium Titanate

Mon, 16 Mar 2009 15:59:34 -0500

Microstructure of polycrystalline BaTiO3 by means of reflection optical microscopy in polarized light. Etched 2.5 min.

Roderic Lakes, Donald Stone (DMR #0520527)[Image390]Barium Titanate was used as an inclusion in composites that achieve stiffness about ten times as great as diamond. A peak in mechanical damping occurs in barium titanate near the Curie point 125C. The height and width of the peak increase with thermal rate and the inverse of frequency. Bulk modulus softens by about a factor of four during the transition. Recent study shows softening of about a factor of ten. Results are consistent with....

Fast Crystal Growth at the Surface of an Organic Glass

Mon, 16 Mar 2009 15:56:38 -0500

Films thicker than 400 nm show this dense crystal morphology, but films thinner than 180 nm show a fibrous morphology.

Y. Sun, K. L. Kearns, L. Yu, M. D. Ediger (DMR #0520527)[Image389]Amorphous indomethacin (an anti-inflammatory drug) crystallizes more than 100 times faster at the surface than in the bulk. A crystal layer spreads quickly across the surface without penetrating the interior.Because of the importance of this process for preparing amorphous pharmaceuticals and for understanding fundamental aspects of crystal growth, we have investigated the thickness of the surface crystals. We conclude....

Synthesis and Design of Catalytic Materials for Selective Production of Bio-Products

Mon, 16 Mar 2009 15:51:16 -0500

Yomaira Pagan-Torres, Paul F. Nealeya, Nelson Cardona-Martinez, James A. Dumesic (DMR #0520527)[Image388]We have synthesized supported metal catalysts for which the structured oxide support has been functionalized for specific applications in the production of chemicals from biomass. The role of the functional groups incorporated onto the support is to interact with specific reactants or solvents in the reaction mixture. The example chosen for study is the selective conversion of furan....

Size-Dependent, Surface-Induced Ordering of Liquid Crystals Observed in Monodispersed Droplets with Micrometer-to-Nanometer Sizes

Mon, 16 Mar 2009 15:01:38 -0500

Representative configuration of mesogens confined within spherical LC droplets with nanometer-scale dimensions, as predicted by simulations. The top figures show cross-sections of the droplets. The bottom figures show the interfaces of the droplet in contact with water (red), which promotes parallel anchoring, and surfactant molecules (green) that promote homeotropic anchoring. At elevated temperatures, the mesogens and surfactant adopt disordered configurations, whereas upon lowering the temperature, the mesogens exhibit nematic ordering and the surfactant at the interface adopts an ordered morphology consisting of regular stripes.

Jugal K. Gupta, S. Sivakumar, Frank Caruso, Nicholas L. Abbott (DMR #0520527)[Image386]It is widely appreciated that the supramolecular ordering of polymers, surfactants and liquid crystals (LCs) can be impacted by confinement. In many cases, however, these effects remain poorly understood. This is particularly true for LCs, where confinement-induced ordering in natural systems (e.g., containing DNA and proteins) underlies remarkable material properties such as the strength of spider silk,....

Nanoimprinted Thin Films of Reactive, Azlactone-Containing Polymers: New Methods for the Topographic Nanopatterning with Facile Post-Fabrication Chemical Functionalization

Mon, 16 Mar 2009 14:54:16 -0500

Schematic illustrations of (A) transfer of nano- and micrometer-scale topographic features to a thin film of a reactive, azlactone-containing polymer using nano-imprint lithography (NIL), and (B) post-fabrication chemical modification of azlactone functional groups by reaction with amine-functionalized nucleophiles. (C) Structures of the reactive, azlactone-containing homopolymer and copolymer used in this study. (D,E) Phase contrast (D) and fluorescence microscopy (E) images of NIH-3T3 fibroblasts (stained with calcein AM) seeded on a film of azlactone-containing polymer imprinted with a pattern of lines at a 4-µm pitch. The dotted arrows indicate the direction of the topographic features. Scale bars = 100 µm (25 µm for inset).

Nathaniel J. Fredin, Adam H. Broderick, Maren E. Buck, David M. Lynn (DMR #0520527)Approaches to the fabrication of surfaces that combine methods for the topographic patterning of soft materials with opportunities for facile, post-fabrication chemical functionalization will contribute significantly to advances in the design of a broad range of functional materials, including biomaterials. IRG3 has developed new methods that can be used to introduce well-defined topographic features into....

Making "Smart" Oxides Using Molecular Layers

Mon, 16 Mar 2009 14:49:49 -0500

[Image381]M. Mavrikakis, R. J. Hamers, T. F. Kuech, P. Gopalan, P. G. Evans (DMR #0520527)Organic molecular layers can provide useful ways to interface oxide materials with organic and biological materials. The Mavrikakis, Hamers, Kuech, Gopalan, and Evans group at the University of Wisconsin MRSEC have collaborated to develop a new way to modify the surface properties of planar ZnO surfaces and of ZnO nanowires. Organic alkenes will graft to ZnO when illuminated with ultraviolet light,....

Dislocation-Free Fully Relaxed SiGe Substrate

Mon, 16 Mar 2009 14:48:08 -0500

Left: Atomic force microscope (AFM) scan of SiGe fabricated by the conventional technique. Root mean square (RMS) roughness is 13 nm. The crosshatch is a sign of severe dislocation formation. Right: AFM scan of our SiGe substrate. RMS roughness = 0.27 nm.

[Image378]B. Tanto, D. E. Savage, M. G. Lagally (DMR #0520527)To make modulation-doped 2-dimensional electron-gas structures for applications in quantum electronics, the requirements on the quality and strain state of the materials for the Si/SiGe heterojunctions are extremely stringent. Defect-free strained silicon and silicon/germanium alloy will be ideal. Such perfect materials currently do not exist. We have developed a new process for fabricating defect-free strained-Si-based....