Sangtae Kim (Chair) 2014 Engineering Hall 1415 Engineering Drive Madison, WI 53706-1691

Tel: 608/262-1092 Fax: 608/262-5434 kim_sangtae@lilly.com www.engr.wisc.edu/che

Explaining and predicting the macroscopic behavior of advanced materials

Molecular Twist

Professor Juan J. de Pablo was one of 20 engineers and scientists in the nation to receive the Presidential Early Career Award for Scientists and Engineers (PECASE) from the National Science Foundation in the last year. Professor de Pablo (pictured in foreground) was recognized for his work in molecular modeling of complex fluids. Using sophisticated molecular-simulation methods and powerful computers, de Pablo examines molecular motion and probes the microscopic structure of advanced materials. Based on these studies, he tries to explain and predict the macroscopic behavior of these systems. For example, de Pablo has found that mixtures of cryoprotectants can act in a synergetic manner to form improved and unique cryoprotectants. His team has developed molecular models that describe quantitatively these findings, thereby providing much needed guidelines for the selection and design of new cryoprotectant systems. This may make it possible to develop glasses for long-term, room-temperature storage of proteins and enzymes. This may enable long-term vaccine storage at room temperature for extended periods of time, facilitating use and distribution in underdeveloped areas where refrigeration is a problem. Kimberly Clark, 3M, Ciba Geigy and DuPont are among the companies that have tapped de Pablo's expertise to design efficient chemical processes or develop new materials. Shown above, de Pablo and research assistant Dan Miller use X-rays to examine the molecular structure of materials (39K JPG).

Targeting polymer flow for improved manufacturing

Fibers in our clothing, films used in nicotine patches and the sticky coatings on adhesive tape are examples of products that are manufactured by melting a polymer and extruding it in liquid form, either as a strand or a coating. Unlike everyday materials such as water, a molten polymer is an elastic liquid, with some memory of how it has been stretched and sheared in the past. At high production rates, this elasticity leads to processing instabilities, through which tiny fluctuations are magnified into wavy distortions of the product, making it unusable. Assistant Professor Michael D. Graham is trying to better understand how polymers flow, and particularly the mechanisms that lead to flow instabilities. With this improved understanding, he is developing strategies for suppressing instabilities, in some cases by judiciously exploiting the very elasticity that leads to instabilities in the first place. This work has attracted the attention of the 3M Company, a world leader in the production of polymer coatings and films. 3M is working to implement some of Professor Graham's ideas and supports his research through the 3M Non-Tenured Faculty Award.

Seeking treatment for Alzheimer's

Associate Professor Regina M. Murphy and Assistant Professor of Chemistry Laura Kiessling have discovered a possible way to inhibit the formation of plaques in the brain, a primary characteristic of Alzheimer's disease. In studying the aggregation of beta-amyloid peptide (Aß) in the brain, Murphy and Kiessling identified specific factors that allow Aß to clump together. Aß has oily parts and water-soluble parts. Aß's oily parts stick together, leading to formation of large toxic clumps. The researchers designed and synthesized molecules which bind to Aß; when these molecules are added to Aß, Aß no longer forms the kind of fibrils that are found on the brains of Alzheimer's patients. Instead, Aß formed short bundles which are no longer toxic in cell cultures. Murphy and Kiessling are working to increase the specificity of the hybrid molecule that prevents fibril formation and toxicity. Eventually they hope to create a compound that can be synthesized into an injectable treatment for Alzheimer's disease.

More spectral range for solid-state devices

Most everyone is familiar with the ubiquitous red light-emitting diode in use in so many consumer applications. Professor Thomas F. Kuech and his team are working to extend the spectral ranges available to solid-state devices. Researchers are developing new semiconductor materials that open up the green, blue and ultraviolet regions of the visible spectrum. Semiconductors based on gallium nitride (GaN) are being developed for applications in optical recording, low-cost lighting, new laser structures, and high-power and high-temperature devices. Through chemical vapor deposition, the work focuses on physics and chemistry of the synthesis of multi-layered semiconductor structures. Kuech has studied the underlying reaction chemistry and its influence on the optimal reactor design and the resulting GaN materials properties. Numerical simulations of the GaN growth reactor have lead to improvements in the uniformity and utility of these materials. Kuech works in collaboration with researchers at the California Institute of Technology as well as with several industrial laboratories.