MSE Research Areas
Computational Materials Science
Materials theory, modeling, and simulation address all classes of materials and materials phenomena. They provide a means of interpreting experiment, summarizing our understanding, explore the origins of observed behavior, and make predictions about structure, property and behavior. This is a golden time for materials theory, modeling, and simulation as (1) materials science and its tools becoming increasingly quantitative and higher resolution, (2) computational power is exploding, and (3) new classes of theoretical and computational formalisms develop. Materials theory, modeling, and simulation addresses all materials length and time scales. At Penn, these range from the electronic (quantum mechanical), atomistic, microstructural, and continuum levels. Increasingly, the forefront of research at Penn focuses on bridging between and integrating these (multi-scale modeling). Current research at Penn focuses on defects in materials, materials processing, two dimensional materials, descriptions of bonding, interaction of materials with electromagnetic radiation, soft materials, biomaterials, mechanical behavior, nanomaterials, and electrochemical systems.
Electronic, Optical and Magnetic Materials
The ability to control functional condensed matter systems with atomic level precision presents endless opportunities to build novel devices and structures and for understanding the chemistry and physics of solid state materials. Precisely engineered low-dimensional materials with tailored properties will lead to new optoelectronic and quantum device paradigms and applications. In low-dimensional materials the interplay of geometry, topology, mechanical deformations and symmetry breaking fields can drastically modify their electronic, optical and photonic properties and produce new phases of matter with tunable responses where the flow of charged carriers, phonons and photons can be exquisitely controlled.New nanoscale materials and their heterostructures are a rich and emerging source for exploring electronic and optical phenomena that are unattainable in conventional material systems. Foundational research on these emerging materials will have significant impact for future applications including quantum computing, photonics and sensing.Current research in MSE includes synthesis and assembly of functional materials, designing new probes and device paradigms to evaluate new theories to expand the fundamental understanding of these materials, and engineering materials, structures and devices with innovative functionalities for future technologies that will also be sustainableand energy efficient.
The basic building blocks in many new material systems are based on structural units with dimensions in the nm range. Tubes and wires with 1 nm widths, microporous structures (pore size < 2 nm), mesoporous structures (pore size between 2-50 nm), macroporous structures (pore size > 50 nm), particles with 30-100 nm diameters, biological molecules with 3-30 nm dimensions, films with 2-100 nm thicknesses, membranes with 10 nm widths, and solids with grain sizes < 500 nm are now routinely produced. This diversity allows new classes of materials to be explored. Earth-abundant non-precious nanoporous materials are being developed for advanced electrochemical energy storage applications. Polymer-drug composites with particle sizes on the order of 100 nms are being developed for drug delivery using a variety of scheme for extended delivery. Hybrid structures that contain organic/biomolecular as well as inorganic structural units are being assembled for bioelectronic applications. Carbon nanotubes are the focus of much research due to potential applications in display technology, molecular electronics, sensors, and as reinforcements in structural materials. Nanodomains in complex oxide compounds are being controlled to induce new property combinations.
Microscopies and Scattering
Modern electron microscopes rely upon the high charge/mass ratio of electrons to probe the local properties of materials with extraordinary resolution. In the department, we have a long tradition of investing in, and applying, the very latest in electron microscope technology to the study of materials. At present, the Electron Microscopy Facility within the Singh Nanotechnology Center has five scanning and transmission electron microscopes that can be used to study the structure, microstructure, chemistry and electronic bonding of materials. Studies of materials at resolutions that allow imaging at atomic resolution are now routinely accomplished by undergraduate and graduate students, and post-doctoral fellows using these instruments. Within the facility, regular training is provided to enable students to integrate electron microscopy studies in their research programs through both classroom and laboratory instruction, as well on an as-needed basis. In the near future, there will be installation of two new scanning transmission / transmission electron microscopes within the facility, one of which will be a first of its kind in the U.S.
Materials for Energy
The inexorable growth in the global demand for energy is raising fundamental problems in resource limitations and environmental pollution. Sustainable generation of electricity potentially provides a means for meeting the world’s growing energy needs without negatively impacting our environment. New materials are essential in the development of innovative carbon-free or carbon-neutral energy generation and storage technologies. A promising example is the conversion of chemical energy into electricity using fuel cells (with polymer or solid-oxide membranes) and batteries (metal-ion, metal-air, metal-sulfur, metal-CO2). Materials advances are essential to increase the cell efficiency and lifetimes, as well as reducing cell fabrication costs. Advanced batteries (e.g., metal-air, metal-sulfur, metal-CO2) require new materials (electrolytes and cathode catalysts) to increase charging speed, improve safety, and extend lifetimes. In addition, porous materials with tunable pore size and surface chemistries are being designed for electrodes in these batteries, as well as for on-demand hydrogen generation by hydrolysis.
Materials for Health Science
Materials continue to enable innovation in the health sciences, particularly in the areas of medical and dental implantable devices, advanced imaging and sensing, tissue stimulation, injury reduction and drug delivery. By the judicious design of the chemical compositions, materials processing methods, investigation of structure-property relationships at micro- and nanoscale, and control of surfaces and interfaces, unique combinations of properties and functionalities can be attained. Materials performance can be advanced by interfacing with biological components, including cells and proteins, and drawing inspiration from nature. Fundamental materials research will ignite future breakthroughs in the healthcare community including responsive implants, tissue engineering and regenerative medicine, infectious disease, therapeutic delivery, diagnosis and repair of injuries, and next-generation imaging and sensing devices, as well as providing model materials for studying biological systems.
Biomaterials encompass all classes of materials that are used in medical applications including tissue engineering, medical implants, and drug delivery. In MSE at Penn, polymers and inorganic materials are being developed to replace bone and blood vessels. Coating are being designed using peptides to control cell attachment and ultimately function. Novel ceramic-peptide composites are also used to control drug release. In addition, theoretical models are being developed to understand the mechanics of biological systems.
The field of structural materials focuses primarily on the mechanical properties and encompasses metals, ceramics, polymers and composites. For structural materials the ideal goal of mechanical behavior is to achieve both high toughness and strength, and often combined with the requirement for weight reduction to improve energy efficiency. Alloying is a common approach to achieve the best possible properties and novel design concepts include disordered alloys, most recently high entropy alloys composed of several components of the same concentration, compounds and composites. Additional topics of interest include mechanical behavior in extreme situations (high temperature, radiation environments), unusual combinations of mechanical properties and low density materials (e.g., high performance polymers, magnesium alloys). An essential aspect of modern structural materials research is establishing fundamental links between mechanical properties and atomic structures extending to microstructure, for example defects in alloys and tie molecules in polymers. Research on structural materials involves experimental techniques such as electron microscopy, synthesis/processing and mechanical testing as well as computer modeling based on fundamental physics and state of the art advancements in continuum mechanics. The overarching goal in structural materials is to develop novel synthesis and processing approaches to manipulate the mechanisms and structures involved in mechanical behavior.
Metals, ceramics, electronic materials, and polymers consume natural resources and energy during their production and fabrication. To ensure a sustainable earth, new strategies are being explored to minimize the consumption of non-renewable resources and lower the carbon footprint for materials processing. For example, the industrial process used to produce aluminum is one of the most energy and carbon-intensive industrial processes in the world, specifically for every kilogram of aluminum 16 kWh of electrical energy is used and 14.8 kg of carbon dioxide is released. Plastics are produced from petroleum-derived chemicals and in the United State the vast majority are used once and then landfilled. Materials scientists are innovating more sustainable strategies to extract, process and recycle materials to significantly reduce both energy consumption and carbon emissions while producing materials for every sector of the economy (infrastructure, computing, packaging, transportation, etc.).
Polymers and Soft Matter
Plastics, rubbers, proteins, epoxies, networks, gels, and such belong to the broad class of materials called polymers, because all of these materials have many (“poly”) small repeat units (“mers”) covalently bonded together. Polymers have unique physical properties due to their considerable molecular size, numerous conformations, and chemical variety. Their properties can be modulated by combining one or more polymers to make polymer blends or by adding nanoparticles to make polymer nanocomposites. Moreover, polymer properties are sensitive to their processing history, which can impact structure and phase transformations, and by confining polymer to thin films, surfaces or nanoporous templates. Within the Department of Materials Science and Engineering at Penn, we have expertise in a wide range of polymers including acid- and ion-containing polymers that can be used for tough thermoplastics and specialty membranes, responsive polymer that change shape and function in response to external stimuli, advanced polymer coatings that reduce infection and capture water, and polymer nanocomposites that exhibit emergent mechanical and optical properties. Many of the topics in polymer materials science overlap with research in the area of soft matter, which encompasses amorphous polymers, colloids and lipids that assemble into hierarchical structures.