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Sustaining Excellence in Chemical Engineering at UCSB

Michael F. Doherty, Chair

The Chemical Engineering Department at UCSB1

The future technological, economic, and strategic success of the United States will depend on a continuing mastery to create and produce desirable new products that others cannot; products that are characterized by complex functionality such as photovoltaics, high-power fast-recharging batteries, pharmaceuticals, responsive materials, etc. The future of chemical engineering is in prediction, not correlation, and this is one of our department’s greatest strengths. Correlations were an important development relative to an earlier era, and remain an important aspect of the engineer’s repertoire. Over the last fifty years, our profession has perfected methods for correlating experimental data for reaction rates, activity coefficients, crystal growth rates, nucleation rates, etc., which provide the foundation for both product and process design. However, only rarely has the profession managed to predict these rates. Predictions assist in making experiments more directed and faster, and they can be especially helpful for product and process invention and design. Predictions are based on a deep understanding of mechanism, experimental facts, and the fundamental underlying physical and biological properties of the system. To be successful requires close collaboration between science and engineering, between experiments and theory, between theory and simulation. And this plays to our strengths. Santa Barbara is renowned the world over for its unique atmosphere of collaborative research at the forefront of science and engineering. The fruit of this research informs our teaching and provides both undergraduates and graduates an evolving curriculum at the vanguard of chemical engineering. We want to produce knowledge that changes the way people think.

has witnessed a meteoric rise in stature during the last 20 years and is now firmly established as one of the top 10 departments of chemical engineering in the United States (see Appendix A for support of this statement). We arrived at this place by encouraging research and teaching of the highest quality and by the slow and careful hiring of the most outstanding faculty, who attracted the most outstanding students. And this is a tradition that we continue today. However, to excel in the future will require more, and this is where you can help.

Research such as I have just described is difficult, brave, and cannot be rolled out like laying carpet. Such ambitious research cannot be scheduled, and milestones can be a moving target. This is completely out of step with current funding models, which are schedule-driven and mission-oriented; or in many cases, training-oriented. Without a Gantt Chart there is little chance of getting your proposal funded! This raises the unanswerable question, “when are you going to schedule your next invention?” Our nation is no longer geared to funding long-term,

1 The department was started in 1965 by Dr. Robert Rinker, graduated its first BS in 1968 and its first PhD in 1971.

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brave thinking research. Students are the main losers since their funding is tied almost exclusively to short-term research grants. Our goal is to become the leading concept-driven (in contrast to proposal-driven) department of chemical engineering in America. We will be the provider of novel solutions to problems that must be solved and we will achieve this by giving our students the freedom to perform their scholarship unhindered, in one of the world’s leading collaborative research institutions with no boundaries. Our metric of success will be impact.

The situation I describe above does not seem to be confined to the world of chemical engineering, as noted in a front page article in the New York Times, Sunday, June 28, 2009 titled, “Playing it Safe in Cancer Research: Grant Money Goes to Projects Unlikely to Break Much Ground.” The article states that, “ with too little money to finance most proposals, they (reviewers) are timid about taking chances on ones that might not succeed. The problem, Dr. Young and others say, is that projects that could make a major difference in cancer prevention and treatment are all too often crowded out because they are too uncertain. In fact, it has become lore among cancer researchers that some game-changing discoveries involved projects deemed too likely to fail and were therefore denied federal grants, forcing researchers to struggle mightily to continue.”

To prepare for the future of high-impact research and teaching, the top departments of chemical engineering will need to attract significant endowment funds to support students engaged in long-term, cutting-edge, game-changing research. Only in this way will our students and faculty be able to work relentlessly on projects dedicated to solving the most pressing problems in energy, carbon capture, manufacturing competitiveness, homeland security, etc. Our department needs to support a minimum of 20 such scholarships for doctoral students, and a similar number for undergraduates in perpetuity. We already attract the very best students at both levels and we owe it to them, to the state and the nation to provide them with an education equal to their ability.

These are challenging times to be seeking endowment funds, but they are for a high purpose and our case rests on a foundation of success that few departments can match.

Current research in the department is focused on three major thrust areas, (1) Systems Engineering, Energy and Catalysis; (2) Polymers and Complex Fluids; and (3) Biological Engineering. What follows is a brief summary of some of the challenging research problems in these areas that our students are working to solve. A more detailed statement is given in Appendix B.

Systems Engineering, Energy and Catalysis. Our department has a strong tradition of accomplishment in process systems engineering. One notable success is residue curve technology for invention and design of complex reactive and azeotropic distillation systems. These methods have been used extensively by industry to invent many new processes that have been patented (e.g., US6,093,842, US6,518,465B2), built, and commercialized In addition, our

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methods are taught in universities around the world. Current research is focused on crystal engineering for product and process design, “on-line” monitoring and control of diabetes in human patients, and systems biology. Two of the important problems we are working to solve in crystal engineering are (1) the elimination of ubiquitous needle-like crystals in pharmaceutical manufacturing which limit productivity and drive up costs significantly, and (2) an economical reactive crystallization technology for removing carbon dioxide from stack gases which has the potential to improve the prospects for electricity generation from hydrocarbon fuels while mitigating climate change. Systems engineers at UCSB are at the forefront of the new field of systems biology which is based on treating the human organism as a holistic interconnected system rather than a large collection of isolated parts. As with classical systems engineering, it is becoming apparent that problems in one part of the system can be overcome by new therapies which are applied to a different, but interconnected part of the system. These approaches promise to revolutionize medicine.

Energy research has been a mainstay of the department at UCSB from its inception. Nuclear engineering was one of the founding subjects in the department which has since been broadened to encompass natural gas to liquids technology, hydrogen production via solar energy routes, catalysis, and renewable fuels. Past successes include the development and commercialization of bromine-based natural gas to liquids technology; now practiced by a UCSB spin-off company (http://www.grt-inc.com/) in its ninth year of operation.

Polymers and Complex Fluids. The polymer group has identified entirely new classes of thermoplastic elastomers based on semicrystalline polyolefin block copolymers and “mikto-arm” styrenic copolymers, which have enabled a two-fold improvement in both strength and thermal stability. These materials are currently being evaluated by several companies for applications in medical devices, body armor, and advanced composites. The associated complex fluids group has recently launched an effort to discover the design rules for nanoparticle surfactants in order to take polymer blending for advanced functional materials to a new level. Another major theme involves microfluidics, in which picoliter samples are manipulated and delivered on microfabricated “laboratories on a chip.” The main goal is to disconnect the “lab on a chip” from its large external hardware systems in order to make it truly portable and self-contained for applications such as blood monitoring and drug delivery.

Biological Engineering. Drug delivery research at UCSB has deep foundations in material science and the establishment of cross-disciplinary research teams spanning chemical engineering, chemistry, biology, and physics to address unmet needs. Drug delivery technologies under development at UCSB range from self-assembling nano-carriers to needle-less ultrasound-enhanced transdermal delivery. Technologies include high-throughput screening of excipient combinations to new approaches for antibody development. Research at the interface between engineering and the molecular sciences at UCSB is creating new paradigms for point of care diagnostics. Rapid, precise, and cost effective diagnostics tools are being developed that are based on research in molecular signal transduction and microfluidics.

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Biological materials and assembly pathways offer advantages over traditional processing methods for materials in medical implants and devices as well as in regenerative medicine. This is possible through the translation of the underlying molecular mechanisms into biologically inspired solutions, e.g., biocompatible and optical transmission materials as well as energy storage materials. A unique instrument pioneered by Israelachvili, the Surface Forces Apparatus is used for directly measuring the forces between surfaces in liquids and vapors, and for studying other interfacial and thin film phenomena at the molecular level. Specific projects currently include: non-equilibrium interactions (e.g., adhesion and friction) to understand how the gecko runs upside down ceilings and walls with the aim of developing the fundamental basis for new classes of responsive materials.

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APPENDIX A

The Chemical Engineering Department at UCSB has 20 full-time ladder faculty (17.2 FTE’s) plus one non-ladder faculty member who has day-to-day responsibility for the undergraduate laboratory. Five of these faculty are members of the NAE, and a sixth is a member of the NAE, NAS, and FRS.

US News and World Report ranks our department number 9 in the US.

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The following data provide rankings based on various measures of research impact.

Research Impact Factor per ChE faculty 1

1. UC-Santa Barbara 18.1 2. Caltech 14.2 3. Stanford 13.2 1

Study conducted by Korean Advanced Institute of Science and Technology, “Highest Impact Universities in Chemical Engineering”, 1999.

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Citations Per Publication 2

1. UC-Santa Barbara 2. MIT 3. Stanford

2

Savage, Chemical Engineering Education, “ChE Rankings: Productivity and Quality Indicators”, 2003.

Our faculty have been honored with many awards for research, including two who were recently honored by AIChE as being among the top 100 Chemical Engineers of the Modern Era (post WWII).

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APPENDIX B

Systems Engineering, Energy and Catalysis (Chmelka, Doherty, Doyle, Gordon, McFarland, Mellichamp, Peters, Scott, Seborg)

Systems Engineering Systems engineering is one of the foundations of chemical engineering that distinguishes

us from chemists, biologists, and other scientists. No matter how the chemical engineering profession evolves in the future, the “systems approach” will remain at the core. The Chemical Engineering Department at UCSB retains a strong emphasis on systems engineering in both teaching and research. The major themes of current interest include: crystal engineering in support of product and process design: “on-line” control of diabetes in human patients; and systems biology. Past successes of this group include residue curve theory for design of reactive and azeotropic distillation systems, and real-time monitoring and control strategies for chemical and petroleum processes. Residue curve design methodology has become a standard feature of all commercial process design and simulation software and has been used extensively to conceive and patent many new reactive and azeotropic distillation systems. Our papers have been cited thousands of times and have been used to rewrite textbooks, handbooks, and lecture notes.

Crystal Engineering for Product and Process Design. Crystal growth is a surface-controlled phenomenon in which solute molecules are incorporated stereo-specifically into surface lattice sites in order to yield the bulk long range order that characterizes crystalline materials. Some key measures of performance for crystalline products include: polymorph (crystal structure), crystal size and shape, and enantiomorph (for chiral molecules). These attributes have a strong influence on such diverse applications as bioavailability and uptake of pharmaceuticals in the body, activity and selectivity of solid catalysts, and efficiency and performance of photovoltaic devices. The Doherty group is interested in all aspects of predicting, manipulating and controlling the properties of crystals, via processing involving some or all of the following steps: nucleation, growth, dissolution, polymorph transformation, solvent effects, and the influence of impurities and additives. A new generation of predictive crystal growth models have been developed based on the underlying growth mechanisms and solid-state chemistry. Applications are mainly focused on organic specialty chemicals and pharmaceuticals, with a growing interest in inorganic materials for battery, photovoltaic and catalysis applications. The group is also initiating projects on a new way of capturing CO2 from stack gases by chemically converting gaseous CO2 at atmospheric pressure into calcium carbonate/cement. This may radically improve the prospects for electricity generation from hydrocarbon fuels while mitigating climate change.

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Figure 1. Predicted shape evolution of a spherical ibuprofen seed crystal grown from aqueous solution. Figure (d) is the predicted steady-state shape, Figure (e) is the experimentally grown shape.

Diabetes. Over the past 10 years the Doyle group has pioneered the application of model predictive control for regulation of insulin delivery to regulate glucose. Their 1999 paper (Parker et al., IEEE TBME) was precedent setting, and numerous companies are currently investigating this methodology for automated insulin delivery (Medtronic, Roche, Diesetronic, etc.). Since 2002 the group has been working with medical collaborators (Drs. Jovanovic and Zisser of the Sansum Diabetes Research Institute) in carrying out human clinical trials of advanced control algorithms for the management of diabetes. The work is characterized by a rich combination of theoretical control principles, such as parametric programming, combined with the critical medical intuition that comes from collaborations and medical trials. In 2007, the Juvenile Diabetes Research Foundation identified the “closed-loop” as one of its top priorities, awarding funding to 6 different international teams to pursue this goal – the Doyle and Seborg groups are key members of two of those teams, leading the algorithm development in both cases. Accomplishments on this project include an automated algorithm to detect the presence of a meal, and an alarm scheme to warn a patient of an impending hypoglycemic incident. Systems Biology. Doyle’s group is a leader on the computational side of the emerging field of systems biology. During the last 8 years their efforts have focused on the rich regulatory architecture underlying circadian rhythm generation in the brains of flies and mammals. Using this model system, Doyle’s group has pioneered the development of sensitivity-based tools for quantifying robustness in oscillatory and stochastic biosystems. The most recent publications from the group are bringing new understanding to the circuitry for circadian rhythm control in Arabidopsis, and the first molecular-based quantitative prediction of the network scale phenomenon of synchronization in a mammalian circadian cellular network (see figure below). Recently, attention has turned to the network aspects of the clock, and new results have shown, using experimentally validated mathematical predications, that phenotypes at the cellular level contradict the behavior observed at the organism or tissue level. This has profound implications for the study of clock neurons in the brain. This work has attracted interest from the pharmaceutical industry, and the group is now part of a $15M Consortium funded by Pfizer to find novel drug targets for type 2 diabetes.

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Figure 2. Michaelis-Menten surfaces and limit cycles (red lines) for expression of circadian clock component Per2 in wild-type mice (left) and Cry2 knockout mice (right). Center plots show simulated time courses for Per2 mRNAs in wild-type mice (solid line) and Cry2 knockout mice (dashed line). Note that the transcription rate makes periodic excursions to relatively high levels in the knockout, when compared to wild-type, accounting for the higher mRNA amplitude seen in the mutant’s simulated time course and also in experiment. Energy and Catalysis (Chmelka, Gordon, McFarland, Peters, Scott) Research activities at UCSB in Catalysis and Reaction Engineering span a wide range from theoretical methods development to fundamental studies of surfaces and interfacial reactions and design of new catalysts for applications in new materials, chemicals and fuels. Past successes include the development and commercialization of new liquid fuel production and chemical processes based on natural gas activation with bromine followed by complete bromine recovery and recycle. The technology is uniquely suited to scaling-down thereby making thousands of small stranded natural gas fields potentially available to produce liquid fuels and chemicals. A UCSB spin-off company (Gas Reaction Technologies, Santa Barbara, CA http://www.grt-inc.com/) is in its ninth year of operation commercializing these technologies. Three UCSB faculty are closely associated with the company (McFarland, Doherty and Stucky). The Chmelka group has a history of forefront contributions in the design of new porous materials for catalysis and other applications. Zeolites are known for their robust, crystalline frameworks, however, their small (sub-nanometer) channel diameters severely restrict the size of molecules that can be processed. The Chmelka group has recently shown that the presence of organosilane additives during synthesis leads to nanocrystalline zeolites with large external surface areas and hierarchical porosity, Figure 3. These materials are versatile catalysts in that they can accommodate very large hydrocarbon molecules. For example, their ability to break polyethylene into smaller fragments, at low temperatures may allow us to recycle plastics into the monomers from which they are derived. Current work in the Chmelka group seeks to understand the role of fluoride and other structure-directing agents in determining zeolite synthesis, motivated by the prospect of creating new classes of porous oxide catalysts.

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Hydrogen is the ultimate clean-burning fuel, but well-meaning proposals to replace fossil fuels such as oil and natural gas by hydrogen often fail to mention that we lack a convenient energy-efficient source. The need for methods to generate hydrogen from non-fossil sources, such as water, is driving research in photocatalysis, in which sunlight provides the energy to split water into molecular hydrogen and oxygen.

2 H2O + sunlight 2 H2 + O2

The McFarland group is designing photoelectrocatalysts for solar hydrogen production. The use of inexpensive, abundant hematite (a-Fe2O3) is attractive because of its smaller bandgap compared to anatase (TiO2), allowing for more efficient capture of sunlight. To improve its catalytic performance, hematite thin films have been co-deposited from solution with other transition metal dopants, such as molybdenum, to improve their conductivity, and their surfaces are modified with fluoride ions to shift the

surface potential. A promising acceleration of the rate of O2 evolution (the rate-determining step) was observed, making the possibility of large-scale hydrogen generation more practical.

Many oxide materials used as catalysts and catalyst supports, particularly in large-scale chemical processing such as the metathesis of olefins to create molecules with new carbon-carbon bonds, are at least partly amorphous rather than crystalline. This makes experimental determination of their structure and the origin of their catalytic activity challenging. The Peters group is exploring the fundamental origins of acidity (both Lewis and Brønsted) in amorphous oxide materials using cluster models and density functional theory. For example, distortion of tetrahedral aluminum sites in silica-aluminas towards lower symmetry four-coordinate geometries leads to a dramatic increase in Lewis acidity, and enhances the Brønsted acidity of neighboring silanols. A systematic variation of cluster structure variables is being explored to identify sites that are most likely to contribute high, medium and weak acidity, and to provide computational guides to their spectroscopic signatures. The ability to design catalysts with a specific acidity type and strength would enable more selective chemical processing with fewer unwanted by-products. A particularly attractive application is the transformation of low-value saturated hydrocarbons of low molecular weight into diesel-range fuels, using a tandem catalyst for alkane dehydrogenation and olefin metathesis.

Catalysis for energy applications is a focus of several research projects in the Scott group which target the selective activation of conventional fuels (hydrocarbons) and second-generation

Figure 3. TEM micrographs of ZSM-5 zeolite synthesized without (upper) and with (lower) an organosilane present.

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biofuels (lignocellulose). Compared to enzymes, robust chemical catalysts have the potential to activate refractory biomolecules faster, at much higher temperatures and on the very large scales commensurate with energy needs. The rapid oxidative disassembly of lignocellulose to processable sugars and other alcohols is a promising catalytic alternative to enzymatic hydrolysis, and a supported vanadium-based system is being designed for high throughput based on batch results with a homogeneous analog. Our solid acid catalyst based on a sulfonic acid-modified mesoporous silica with a sulfone promoter effects the selective conversion of sugars to furfurals, key platform chemicals which are precursors to fuels and chemicals. The Scott group is working on tandem catalytic systems to achieve multiple reaction steps in a single reactor. For example, sequential sugar hydrolysis followed by furfural oxidation or reduction increases the yield of the desired product by avoiding side-reactions of the furfural intermediate. In an independent effort, tandem catalytic upgrading of light fractions of petroleum leads to a significant increase in their fuel value, by converting butanes and hexanes to diesel-range alkanes. The approach avoids the energy-intensive formation of olefins as isolable intermediates; instead, a dehydrogenation catalyst working in tandem with an olefin metathesis catalyst achieves the upgrading using very low steady-state olefin concentrations. A similar metathesis catalyst finds use in the upgrading of biodiesel, making its fuel performance and long-term stability much closer to that of conventional diesel. Finally, the Scott group is developing emissions control catalysts to facilitate the adoption of higher-energy value fuels (such as diesels) without compromising air quality, and with little or no need for scarce platinum-group metals. For example, copper- and iron-based oxide catalysts have been found to be effective for low-temperature NOx removal from exhaust gas streams. The Department has a team of engineers let by Mike Gordon that is developing new one-of-a-kind instruments and methodologies to probe and image the chemical, optoelectronic, and mechanical properties of novel materials at nm-scale spatial resolutions. The aim of this work is to invent and build new characterization tools and approaches for localized interrogation of interfacial phenomena in challenging venues to better understand and engineer micro- and nanostructured materials for energy conversion, catalytic, optoelectronic, chemical sensing, and bio applications. These instruments are not available off-the-shelf and provide the researchers at UCSB with advanced experimental tools that are not available anywhere else in the world. As an example, Fig. 4 shows how spatially-correlated, wavelength-resolved photo-luminescence and Raman imaging of a plastic solar cell film (polythiophene/fullerene blend) can be used to evaluate phase mixing, optical response, and charge transport at the microscale. The intent of the experiment was to attribute local areas of low photo-luminescence with good [nanoscale] mixing of the donor polymer (P3HT) and fullerene acceptor (PCBM); when mixing is good, the P3HT donor should not photoluminesce because it transfers photo-generated electrons to PCBM. However, Fig. 4 clearly shows that this conclusion (from the photo-luminescence image) is totally false because the Raman images unequivocally prove that the donor polymer is not present in the regions of low photo-luminescence. It should be stressed that traditional

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measurements of solar cell efficiency cannot reveal any of these details, and that this combined photo-luminescence and Raman analysis is the only way to directly correlate phase mixing, local chemistry, and optical activity with film processing and device fabrication procedures. Similar measurements using the scanning chemical microscope tip for localized Raman and conductivity measurements will truly revolutionize our understanding and development of these materials for low-cost, eco-friendly energy-conversion devices of the future.

Figure 4. (a) P3HT donor and PCBM acceptor. (b) Confocal photoluminescence image at 620nm of a P3HT/PCBM film using 488 nm excitation. (c) Raman signal from the image in panel (b). (d-g) Confocal Raman images of the same area at specific P3HT vibrational excitations as shown.

Polymers and Complex Fluids (Fredrickson, Kramer, Israelachvili, Leal, Squires, Zasadzinski) Polymers The polymer group is engaged in a wide range of research activities, many with sponsorship by industry. Working in tandem with Mitsubishi Chemical and Kraton Polymers, Fredrickson and Kramer have identified entirely new classes of thermoplastic elastomers based on semicrystalline polyolefin block copolymers and "mikto-arm" styrenic copolymers. Their research has utilized novel theory and simulation in combination with state-of-the-art experimental methods to optimize strength and softness within these new classes of advanced polymers. One particularly remarkable achievement is the design of a styrenic block copolymer that functions as an elastomer with more than double the styrene content of conventional triblock designs; this has enabled a two-fold improvement in both strength and thermal stability. A further advance connected to the semicrystalline polyolefin materials involves the discovery of a gel processing technique whereby ultra-strong elastic film and fiber can be created with an

Low PL

High PL

50x50 µm2 PL @ 620nm

723 cm-1 1377 cm-1 1448 cm-1 2900 cm-1

C-S-C of thiophene C-C of thiophene C=C of thiophene C-H

δC-S-C

νC-S

νC-Cthiophene νC=C

thiophene ring

νC-H

488 nm pump

Raman

Ph

(a)

(b) (c)

(d-g)

P3HT

PCBM

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(Top) Schematic representation of pattern transfer from copolymer thin films; PEO domains are omitted for clarity. (Bottom) SEM top view and 75° cross-section images of square arrays of cylindrical pores in silicon oxide after RIE and O2 plasma treatment of a UV-degraded thin-film blend of supramolecular block copolymers. (Inset) Magnified SEM top view.

exceptionally broad range of stress-strain behaviors. These materials are currently being evaluated by Mitsubishi and several third parties for applications in medical devices, body armor, and advanced composites. A third program relates to the design and optimization of new polymeric materials and processing techniques for the field of block copolymer lithography. This activity is aimed at utilizing thin film polymer self-assembly to define sub-50 nm patterns and features that can be transferred to a semiconductor substrate and thereby pattern microelectronic devices on length scales inaccessible to conventional optical lithography. Supported by the Semiconductor Research Corporation and other industry and defense organizations, Fredrickson and Kramer have joined forces with Hawker of UCSB's Materials Research Lab and produced a wide range of innovations, including the first demonstration of square lattices of 10 nm cylindrical features (figure at right) and novel graphoepitaxial techniques for achieving defect-free assembly over 5 micron scale regions of a wafer. Complex Fluids The research activities of the complex fluids and transport group seek to harness and control the flow and evolution of fluids and materials for applications in medicine, and microfluidic “labs on chips.” Zasadzinski has forged new understanding of the physics and physiology of the lung surfactant layer, which lines the lung’s air sacs and enables respiration by lowering surface tension. The absence or malfunction of this surfactant layer generally leads to severe respiratory distress and death. Zasadzinski showed that the viscosity of this surfactant layer is crucial in keeping the surfactant in the deep lung, and Squires has developed a novel technique to measure the visco-elastic properties of the monolayer, while directly visualizing its deformation under flow (see figure). This enables key insight into the function of various additives (proteins, cholesterol, and lipids), which play important (but unknown) roles in the natural and synthetic replacement surfactants under development for clinical use. Leal’s studies in the stability, coalescence and break-up of emulsion droplets and bubbles are world-renowned and have led to both predictive models and new strategies for emulsification and bending of viscous, multiphase materials; he has also developed an internationally recognized program aimed at understanding the relationship between polymer chain architecture (e.g., linear versus various classes of branched polymers), and the way that these fluids respond to and influence flow/processing behavior. All of these studies are aimed at the dual problem of understanding the relationship

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Interfacial micro-rheometer, electromagnetically torques micron-scale ferromagnetic disks (inset) that are engineered to sit within surfactant layers at fluid/fluid interfaces. (right) Microdisk embedded within a lung surfactant layer, visualized during the viscosity measurement.

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between the microstructure of complex fluids and flow, and of understanding how flow may be used to manipulate the microstructure to achieve new materials with desired properties. More recently, he has turned his attention to the formation and stability of vesicles and vesicle

suspensions. Although these materials are currently used in many commercial home and personal care products, a rational basis for material design which optimizes product stability and properties is largely lacking. Leal and his group have recently begun to investigate how nanoparticles function as surfactants in stabilizing polymer/polymer emulsions. In particular, Leal and Squires, in partnership with a multidisciplinary group at the Materials Research Laboratory, have launched an effort to discover and understand “design rules” for nanoparticle surfactants, in order to take polymer blending for advanced functional materials to a new level. Their

study has been enabled by novel, micro-scale measurement techniques they have developed. A third major theme involves microfluidics, in which picoliter sample volumes are manipulated and delivered on microfabricated “laboratories on chips,” enabling large-scale, automated and parallelized experimentation and synthesis while consuming minute quantities of reagent. Robust and versatile techniques now exist that enable thousands of fluidic chambers to be designed and independently addressed on chip; however, all such techniques require bulky external hardware, such that the “lab on a chip” must remain “in the lab”. Squires is developing a versatile method for microfluidic manipulation that would be truly portable and self-contained, enabling portable and even implantable microfluidic devices e.g. for blood monitoring and drug delivery. Theofanous pursues fundamental research into interfacial instabilities, compressible multiphase flows, and uncertainties in risk assessment, which he integrates towards optimizing the behavior of real systems, such as nuclear reactor safety, explosive dissemination of liquids and other homeland security applications. His laboratory has developed a unique one-of-a-kind apparatus for imaging liquid drop breakup under the impact of supersonic shock waves which provides new insights for improving homeland security. Biological Engineering (Daugherty, Doyle, Han, Israelachvili, Mitragotri, Shell, Zasadzinski) Research in Biological Engineering spans a variety of topical areas including biochemical and biomedical engineering, biomaterials, and biotechnology. Projects range from the design and engineering of new biomolecules for sensors, medical diagnostics and therapeutics, to drug delivery and implantable biomaterials. The department houses five state-of-the-art biological engineering laboratories, and two computational design and simulation facilities. Scott Shell’s group is developing computational simulation methods enabling the protein design and structure prediction. Protein and peptide molecules are being discovered by Patrick Daugherty’s group and

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tailor engineered to enable diagnosis of cancer, cardiovascular, and autoimmune diseases using protein engineering and display technologies (Daugherty). The Mitragotri laboratory develops and applies novel methods, particles, and devices enabling precise and targeted delivery of pharmaceuticals to improve therapeutic outcome and quality of life. Zasadzinski’s group is developing remote triggered nanoparticles for the selective targeting and removal of diseased cells from the body. His group also investigates the fundamental mechanisms of lung surfactants used to treat respiratory distress. Frank Doyle, Associate Director of the Institute for Collaborative Biotechnologies (ICB) and Director of the Pfizer supported Insulin Resistance Pathways project, develops and applies systems biological methods to address fundamental and applied problems in biology and medicine. Department faculty also play key roles in multiple collaborative bioengineering research centers including a Program of Excellence in Nanotechnology (PEN) for the treatment of Cardiovascular Disease, and a Cancer Center of Nanotechnology Excellence (CCNE). Israelachvili’s group applies sophisticated experimental methods and instrumentation to investigate intermolecular and surface

interactions in biological systems, with applications in the development of advanced biocompatible and multifunctional biomaterials. Geckos and smaller animals such as flies, beetles and spiders have extraordinary climbing abilities: they can firmly attach and rapidly detach from almost any kind of surface. In the case of geckos this ability is attributed to the surface topography of their attachment pads which are covered with fine columnar structures (setae). Inspired by this biological system, various kinds of regularly structured or ‘patterned’ surfaces are being fabricated for use as responsive adhesives or in robotic systems (see Figure 5). We have theoretically analyzed the adhesion and friction forces

of patterned surfaces against smooth surfaces by applying well-established theories of van der Waals forces together with the classic Johnson-Kendall-Roberts (JKR) theory of contact (or adhesion) mechanics to recent experiments on adhesion-controlled friction. Our results suggest some scaling criteria for simultaneously optimizing the adhesion and friction of patterned surfaces. In particular, we show that both the van der Waals adhesion and friction forces of flexible, tilted, and optimally-spaced setal stalks or synthetic pillars are strong enough to support not only a large gecko on rough surfaces of ceilings (adhesion) and walls (friction), but also a human being if the foot or ‘toe pads’ – effectively the area of the hands – have a total area estimated at ~230 cm2. The research provides models for designing smart and especially switchable adhesive and frictional materials for a variety of adhesion and robotic applications.

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Figure 5. SEM images of surface structures on real and synthetic attachment pads. (A) beetle, (B) fly, (C) spider, (D) Gecko, (a)-(f) SEM images of typical fabricated patterned surfaces. The adhesive pads are circled. In geckos

these are referred to as spatulae and are attached at the ends of the setae.