ON PREPARING TUNABLE RANDOM COPOLYMERS BY “CHEMICAL PAINTING” OF SYNTHETIC HOMOPOLYMERS
Jan Genzer
Department of Chemical & Biomolecular Engineering
North Carolina State University

Heteropolymers with adjustable monomer sequences (HAMS) represent a new type of functional random copolymers that could play an important role in emerging areas pertaining to interfacial science and polymer assembly. HAMS are synthesized in a laboratory by “coloring” the segments of a collapsed homopolymer (say, A) with a functionalizing agent (say, B) and then unraveling the resultant polymer to yield a random sequence of A and B segments, which “remembers” its original collapsed conformation and hence prefers some conformations over others. In the presentation, we will provide details pertaining to the experimental formation of HAMS and studying their physico-chemical characteristics. We will provide examples of a few case studies that unravel the tailorable interfacial and bulk self-assembly character of HAMS made of poly(styrene-co-4-bromostyrene) and its derivatives. Results of computer simulation studies will also be discussed that provide molecular insight into forming HAMS.

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LINKING SCIENCE, INNOVATION, AND POLICY TO TRANSFORM THE WORLD’S ENERGY SYSTEMS – THE MIT ENERGY INITIATIVE
Robert C. Armstrong
MIT Energy Initiative and Department of Chemical Engineering
Massachusetts Institute of Technology

Professor Robert C. Armstrong is the Chevron Professor and former Department Head of Chemical Engineering at the Massachusetts Institute of Technology (MIT). He completed his undergraduate studies at the Georgia Institute of Technology with highest honors and hi PhD at the University of Wisconsin, Madison, in Chemical Engineering. Professor Armstrong has received a number of awards, including the AIChE Warren K. Lewis Award, AIChE Professional Progress Award, the Bingham Medal from the Society of Rheology, the University of Wisconsin-Madison Distinguished Service Citation, and election to the Georgia Tech Academy of Distinguished Engineering Alumni. His two-volume book, “Dynamics of Polymer Liquids” has been named a Citation Classic. He is a member of the National Academy of Engineering.

Professor Armstrong will talk about the global challenge of providing sustainable energy sources to meet the demands for quality of life and economic growth in both the developed and developing world. The need for addressing this energy challenge is greater than at any time in the recent past. This is driven by several factors that together constitute a “perfect storm” requiring our response. These drivers include supply and demand, security, and environmental concerns. Consider that over the next half century global energy use is expected to double and global electricity demand is expected to triple. These increases will call for a significant increase in fossil fuel supplies; alternatively enormous changes in global energy infrastructure will be required. Security concerns are highlighted by the geographical and geopolitical realities of the locations of energy supplies and of the primary users of these resources, principally oil and natural gas. Finally, carbon dioxide emissions associated with combustion of fossil fuels are increasingly of central concern in global climate change. This concern will drive decisions about the evolution of the global energy system, namely whether it will evolve in a business-as-usual path or whether we will turn to less carbon intensive or carbon-neutral energy sources.

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USING THE TUNABLE PROPERTIES OF GAS EXPANDED LIQUIDS TO CONTROL NANOPARTICLE DEPOSITION AND SEPARATION PROCESSES
Christopher B. Roberts
Uthlaut Professor and Department Chair
Department of Chemical Engineering
Auburn University, AL 36849

Full exploitation of nanoparticles and their novel properties for application in areas such as catalysts, optical systems, electronic devices, and sensors requires the ability to effectively process and maneuver particles onto surfaces or support structures. This is often performed by simply evaporating a liquid solution containing ligand stabilized nanoparticles to leave behind dry nanoparticles coated on a surface. However, solvent dewetting and capillary forces at the liquid/vapor interfaces can lead to film defects such as nanoparticle islands, percolating networks, ring-like particle arrays, and uneven particle concentration.

We have developed a novel particle deposition technique which utilizes carbon dioxide as an anti-solvent for low defect, wide area metallic nanoparticle film formation employing monodisperse silver, gold and other metal and semiconductor nanoparticles. Ligand stabilized nanoparticles are precipitated from organic solvents by controllably expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid then provides for removal of the organic solvent while avoiding the dewetting effects common to evaporating solvents. These dewetting effects and interfacial phenomena can be very detrimental to nanoscale structures. Controllable expansion of the liquid solution via CO2 injection allows for control over the thermophysical properties that govern this deposition and assembly process. This gas expanded liquid driven nanoparticle deposition process has been utilized to create thin films of nanoparticles on device surfaces, such as MEMS devices, without the detrimental interfacial dewetting effects inherent to liquid evaporation driven nanoparticle deposition techniques that would otherwise destroy these devices. Our research has shown that gold nanoparticles can be uniformly deposited onto the surfaces of polysilicon microdevices to significantly reduce adhesion and stiction.

In addition, we have extended the application of this CO2 expanded liquid deposition process to an improved method for narrowing the particle size distribution of ligand stabilized nanoparticles. Our implementation allows for the extremely easy partitioning of multiple sized, monodisperse populations almost simultaneously. We have shown that multiple monodisperse nanoparticle populations can be easily isolated from one another and from the organic solvent through controlled pressurization and deposition. Polydisperse Au, Ag and CdSe semiconductor particles (2 to 20 nm) were efficiently fractionated into +/-1nm monodisperse fractions. This tunable gas expanded liquid approach allows for rapid and efficient size separation while also reducing organic solvent usage and has been demonstrated at process scales ranging from microliters to >100 milliliters of an organic nanoparticle dispersion.

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BLOCK CO-POLYMER NANOPATTERNING AND ITS USES IN SEMICONDUCTOR STRUCTURE FORMATION
Thomas F. Kuech
Department of Chemical and Biological Engineering
University of Wisconsin – Madison

There has been a tremendous body of research into the development of nanoscale objects and materials. While these materials exhibit unique properties on their own, the technological development of these materials requires their integration into existing and evolving device and materials platforms. A self-assembled block co-polymer (BCP) approach to nanoscale patterning, which offers rapid and cost-effective full wafer patterning at the 20-nm length scale, is finding applications in the wafer-scale development of nanoscale structures. This talk will deal with several new applications of this approach used to achieve improvements in heteroepitaxial growth of large lattice mismatched materials and the formation of uniform nanostructured device structures, such as Quantum Dots for laser applications.

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The devil is in the details: Exploring transport mechanisms in fractured porous media using X-ray microtomography
Zuleima T. Karpyn
Department of Energy and Mineral Engineering
Pennsylvania State University

Forced mobilization and spontaneous migration of fluids in underground formations are severely impacted by the presence of fractures, which vastly dominate the overall conductivity of rocks. Uncertainties in the description of transport properties in these systems often make flow predictions a difficult task. Understanding the origin of such transport properties and their dependence on local heterogeneities and other geological features is essential for the design of effective recovery strategies. High-resolution X-ray computed tomography allows us to explore these heterogeneities and their impact on fluid transport with realistic detail. This presentation shows a series of experimental findings of two-phase flow in fractured cores, with the aid of micro-scale visualization of fluids, fracture, and rock matrix.

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OXIDATION AND REACTIVITY OF TRANSITION METAL SURFACES
Aravind Asthagiri
Department of Chemical Engineering
University of Florida
Gainesville, FL 32611

Transition metals (TM) serve as catalysts under oxygen-rich conditions in applications such as natural gas combustion, exhaust gas remediation in lean-burn engines, and the selective oxidation of organic compounds. Under oxygen-rich conditions the metal surface can undergo several structural changes as it begins to oxidize, which in turn can dramatically modify the reactivity of the catalyst. Despite advances in our understanding of the oxidation of several catalytically important TM surfaces there is still disagreement in the exact surface phase that is associated with enhanced reactivity in systems such as CO oxidation on Pt. Therefore there is a need to better understand (1) the oxidation process and the structure of the oxygen phases that develop under various conditions (temperature, partial pressures) and (2) the resulting modifications in reactivity of the catalyst.

In this talk, I will first discuss work in our group examining the initial atomic-level steps in the oxidation of Pt and Pd(111) surfaces using Density Functional Theory (DFT), an accurate first-principles method. We have found a novel mechanism for the initiation of oxidation on Pt(111) that results in strongly buckled 1-D oxide chains on the Pt(111) surface. On Pd(111) this mechanism does not occur but instead subsurface oxygen becomes stable at lower oxygen concentration. I will discuss the differences in Pt and Pd that lead to these differences in oxidation mechanisms. I will also present some preliminary results in understanding the reactivity of CO and NO on the 1-D oxide chains on Pt(111). In the second part of my talk I will present examples from our DFT study of several small molecules (H2O, H2, CO, and CH4) on the major oxide surfaces that form on Pd(111). We have found dramatic differences in reactivity between the 2D oxide phase that initially forms on Pd(111) and the bulk oxide that develops at higher oxygen concentrations. These differences can be attributed to changes in both the geometric and electronic structure of the different oxide surfaces. Our work provides new insight into the kinetics of oxidation of TM surfaces and demonstrates the sensitive link between atomic-level structure of the oxide and the reactivity of the oxide phase.

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CARDIOVASCULAR TISSUE ENGINEERING BASED ON CELL-REMODELED BIOPOLYMERS
Robert Tranquillo
University of Minnesota

We are attempting to develop engineered cardiovascular tissues based on the approach of entrapping cells when forming a collagen or fibrin gel within an appropriate mold. The cell induced contraction of the gel's network of native protein fibrils is harnessed by applying appropriate mechanical constraints to obtain the desired alignment of fibrils and cells, that which is characteristic of the target tissues. The beneficial effects of long-term cyclic stetching of the tissue constructs are presented, including evidence that cells adapt to a constant strain amplitude. Application of these strategies to a tissue-engineered heart valve are highlighted.

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A NEW WAY TO LOOK AT DIFFUSION (AND RELAXATION) IN MIXED POROSITY SYSTEMS
Larry Schwartz
Schlumberger-Doll Research
Earth, Atmospheric and Planetary Sciences, MIT

Many porous media exhibit a wide range of pore sizes. One often sees macro-pores that are 20–50 microns in diameter and micro-pores whose size can be roughly 100 times smaller. Spatially, the macro and micro-pores can be arranged either in series, in parallel or a combination of the two. In such systems, the simulation of transport properties and diffusion presents a serious computational challenge. Using a combination of fixed step size and first passage random walk techniques, we calculate electrical transport, the time development of the effective diffusion coefficient, D(t), and surface-induced proton spin relaxation. In treating magnetic resonance, the enhanced interfacial relaxation determines the degree of coupling between the two pore populations. Our calculations employ models based on grain packing and on images obtained by micro-CT imaging of real systems.

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ELASTIC MODULI OF POLYMER THIN FILMS: CORRELATION AND MANIPULATION OF MECHANICS AT THE NANOSCALE
Bryan Vogt
Arizona State University

Mechanical properties of polymeric materials are critical to their utility in many applications. However, little is known regarding the mechanical properties of polymers when confined to dimensions approaching their intrinsic molecular size (R_g). Thermal properties, in particular the glass transition temperature (T_g), of nanoconfined polymers have been studied extensively over the past two decades due to the relative ease of measurements. Correlations between T_g and modulus are well established for bulk polymers, but it is unclear if these hold at the nanoscale. Here, I will present direct comparisons of the thickness dependent T_g and elastic moduli behavior of poly(n-propyl methacrylate) to address this question. Additionally, correlations between bulk T_g and the thickness dependent behavior will be explored by using a homologous series of poly(n-alkyl methacrylate)s and a series of widely varying molecular mass polystyrene films. Finally, two different approaches to manipulate the elastic modulus of ultrathin (< 50 nm) polymer films are discussed in the context of improving the mechanical stability of polymeric nanostructures.

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High Resolution Imaging Technology: a View of the Future
Grant Willson
Departments of Chemistry and Chemical Engineering
University of Texas
Austin, TX

The National Nanotechnology Initiative has focused hundreds of millions of dollars into research related to nanoscale structure fabrication. Government agencies have great expectations for the influence of this research on the world economy. Meanwhile, the drive to manufacture semiconductor devices with ever smaller features has inspired amazing improvements in imaging materials science and technology for decades. The most advanced microelectronic devices in production have minimum features in of 45-50nm and fully functional transistors with 10nm gates have been reported. The lithographic process used to generate these “nano-structures” is becoming extremely expensive and the cost of that process threatens the economics of the semiconductor manufacturing industry. Imprint lithography, a much lower cost, high resolution patterning technology is emerging as a potential adjunct to photolithography. The state of high resolution imaging materials and processes for production of devices with nanoscale features will be presented with emphasis on Step and Flash Imprint Lithography.

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OVERCOMING BARRIERS AND MODELING CHALLENGES IN NATURAL GAS SCIENCE AND ENGINEERING: CASE STUDIES
Luis Ayala
Department of Energy and Mineral Engineering
Pennsylvania State University

Meaningful research in energy science and engineering must address the technology and infrastructure challenges associated with natural gas’ emergence as the world’s premier energy commodity in the 21st century. Experts have labeled this transition to natural gas as a historical imperative and part of the decarbonization of fuels process that has taken place during the history of human energy use. In this presentation, we examine a few instances of modeling challenges in natural gas science and engineering and discuss current modeling efforts aimed at overcoming potential barriers to a swift transition to a natural gas powered society. In the natural gas reservoir arena, current modeling efforts are able to show how multimechanistic flow can play a significant role in the understanding of recovery mechanisms from naturally fractured tight reservoirs hosting retrograde gases. It is also shown how thermodynamic science coupled with fluid flow principles can hold the answer to whether or not real-time acquisition of wellbore temperature data holds any promise for smart field monitoring technology in natural gas reservoirs. In the area of natural gas transportation, the strategic significance of the natural gas pipeline transportation infrastructure is recognized and the significant pitfalls of standard pipeline network analyses are highlighted. Current modeling efforts show, for example, that the answer to increasing capacity in our aging pipeline network transportation infrastructure might lie in the removal of (instead of addition of) pipeline links from the system currently in operation—akin to the Braess’ paradox of traffic flow, the effects of which have been systematically overlooked in the case of natural gas networks. In addition, while network performance analysis is well-understood for single-phase flow, multiphase flow effects that result in fluid re-distribution and the creation of preferential fluid traveling paths are commonly neglected because they are poorly understood. Findings reported in this presentation quantify the consequences of neglecting fluid misdistribution in terms of loss of network capacity and predict where fluids would migrate given a particular network topology and operational conditions.

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WATER AT THE NANOSCALE: FROM DENSITY FLUCTUATIONS AND CORRELATIONS TO HYDROPHOBICITY
Shekhar Garde
Rensselaer Polytechnic Institute

Water-mediated interactions (e.g., hydrophobic interactions) govern a host of biological and colloidal self-assembly phenomena from protein folding, and micelle and membrane formation, to molecular recognition.

At the macroscopic level, hydrophobicity of interfaces is often characterized by the droplet contact angle measurements. Molecular signatures of hydrophobicity have, however, remained elusive. Contact angle measurements are not possible for submerged surfaces or for surfaces of proteins and nanoparticles. How are the properties of water influenced by the hydrophobicity of an interface? Specifically, what are the molecular signatures of hydrophobicity that are consistent with macroscopic expectations? Results of extensive molecular simulations of hydration of a broad range of interfaces demonstrate that water density fluctuations (and not the average local density) provide a quantitative characterization of the interface hydrophobicity. Density fluctuations as well as water-water correlation length are enhanced at hydrophobic interfaces and suppressed near hydrophobic ones. Simulations also show how properties of water at interfaces influence solute binding, folding, and dynamics at interfaces. In addition, I will briefly tell a story of how simulations and science have merged with arts and entertainment to develop an upcoming IMAX movie, Molecules to the MAX.

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NEW INSIGHTS INTO THE MECHANISM OF HYDROLYSIS OF SODIUM BOROHYDRIDE
Michael A. Matthews
Professor & Chair Department of Chemical Engineering
University of South Carolina

Chemical hydrides have excellent theoretical potential as a compact medium for hydrogen storage at low temperatures and pressures. Hydrogen is produced when a chemical hydride, such as NaBH₄, exothermically reacts with water.

NaBH₄ + (2+x) H₂O → 4H₂ + NaBO₂ • xH₂O + heat

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