The Materials Research Science & Engineering Center (MRSEC) at the University of Pennsylvania pursues a multidisciplinary approach to solve fundamental materials problems that are likely to underlie future technologies, and thereby, substantially impact the research and educational needs of society. The Laboratory for Research on the Structure of Matter (LRSM) is the intellectual focal point of materials research at PENN. It hosts the MRSEC, which consists of four Interdisciplinary Research Groups (IRGs) plus continually evolving Seed projects. The MRSEC provides crucial support for faculty, postdoctoral fellows, and graduate students drawn from different disciplines, to tackle complex materials science projects that can only be addressed in a truly collaborative mode. In this way, the MRSEC exploits PENN's strength in the design, synthesis, characterization, theory and modeling to create and understand entirely new classes of materials. The broad expertise, sophisticated equipment, plus the technical and administrative infrastructure that exist in the LRSM enable these projects.
The LRSM plays a special role on the PENN campus: It facilitates collaborations between faculty from different departments and schools, and it promotes links to partners in industry, government, academe, and society at large. The LRSM has experience in managing IRGs, nurturing Seed projects, and acquiring, building and maintaining shared experimental facilities (SEFs) for the benefit of the materials research community. The LRSM provides education & outreach in this "research" context and has moved aggressively in the area of human resources development (HRD) through programs that target students at all levels from K-12 to post-docs, teachers, small college faculty, regional academic, industrial & governmental scientists, the international scientific community, and the general public. A primary goal of our education and human resources development effort is to attract more Americans to STEM fields and take them to the highest educational level possible, with emphasis on underrepresented minorities, women, and the disabled. A second goal is to educate the general public about important ideas in materials science & engineering and about the societal relevance of the materials field.
IRG Leaders: Kathleen Stebe & Randall D. Kamien
Senior Investigators; Tobias Baumgart, Peter Collings, Dennis E. Discher, Tom C. Lubensky, Ravi Radhakrishnan, Shu Yang, Arjun Yodh
Soft matter conforms, assembles, and reconfigures in response to the geometry and chemistry of bounding surfaces and interfaces. IRG-1 aims to harness these effects to create new responsive materials and structures using complex fluids, embedded particles, micro-patterned substrates, and confining volumes. The substrates and particles will be designed with topographies, geometries, and surface chemistries selected to impose constraints on complex fluids, including wetting conditions to three-phase contact lines, anchoring conditions to liquid-crystal director fields, and curvature gradients to fluid interfaces & lipid bilayers. In this way fuller understanding of how such factors affect physical properties of soft materials will be developed, and this understanding will be used to create new materials with distinctive, dynamically reconfigurable structures and to develop design rules for controlling positions, orientations, and migration of "particles" on and within these structures.
IRG Leaders: Daniel A. Hammer & Virgil Percec
Senior Investigators; Jason A. Burdick, William F. DeGrado, Mark D. Goulian, Paul A. Heiney, Daeyeon Lee, and Michael L. Klein
IRG-2 will create new materials, inspired by virology, from self-assembled Janus dendrimers and designer proteins. These new materials, with virus-like structures and functions, will be useful for sensing, communication, and response. Self-assembling amphiphilic Janus-dendrimers (JDs) - dendrimers with two faces, one hydrophilic and one hydrophobic - will be used to build novel nano-structures which will be equipped with components to amplify signals, inactivate viruses, and harvest energy. The IRG will engineer novel functionality into JD-vesicles (JDVs) using the structure of nature's viruses as a guiding principle. Specifically, the IRG will design, synthesize, and characterize functional virus-like JDVs using an array of experimental tools, guided by state-of-the-art computer simulations. The collective effort of the group will be directed to design and optimize JD building blocks and peptide motifs that enable self-assembly and the integration of components into functioning virus-like nano-systems, containing self-assembling protein capsids and/or active sensory components, to ultimately produce entirely new smart nano-materials.
IRG Leaders: Robert W. Carpick & Andrea J. Liu
Senior Investigators; Paulo E. Arratia, Douglas Durian, Dan Gianola, Jerry P. Gollub, Daeyeon Lee, Ju Li and Arjun G. Yodh
IRG-3 studies disordered packings of atoms, nanoparticles, colloids and grains with a goal to to understand how localized rearrangements organize under extreme load to form shear bands, and thereby to develop ways of predicting whether systems are about to fail, and to make new, tough materials by designing their vibrational properties. In condensed matter systems, disordered packings are pervasive. Yet our fundamental understanding of the mechanical response of disordered packings lags far behind that for crystalline ones. In particular, the mechanisms controlling mechanical instabilities that lead to failure are not understood. This scientific gap impedes applications of materials such as bulk metallic glasses, amorphous thin films, and nanoparticle assemblies. To gain new insights into the failure process, the onset of mechanical instabilities and failure will be studied in disordered systems across a range of constituent particle sizes, from packings of atoms to packings of macroscopic grains. This comparative approach brings together researchers from fields that are currently disparate. IRG-3 leverages this collective expertise to study shear band formation and the onset of mechanical failure at each scale: (1) atoms in carbon-based films and metallic glasses; (2) nanoparticles in layer-by-layer (LbL) assemblies; (3) colloidal glasses; and (4) granular media. The atomic and nanoparticle systems are chosen because their mechanical properties are important in applications. The colloidal and granular systems are chosen both for their materials importance and as model systems that are straightforward to visualize and that offer fine control over particle interaction and particle shape and size distributions. The IRG's long range goal will be to use this knowledge to develop and test new design rules for fabricating novel materials with otherwise unattainable mechanical stability.
IRG Leaders: Cherie R. Kagan & James M. Kikkawa
Senior Investigators; Marija Drndić, Nader Engheta, Jennifer Lukes, Christopher B. Murray
IRG-4 will identify, understand, and ultimately exploit the novel collective interactions that arise in highly-ordered, multi-component materials assembled at the nanoscale. These materials are “interdimensional” in that complex interactions between low-dimensional constituents (nanoparticles) organized into higher-dimensional assemblies give rise to surprising and even transformative characteristics. All of the matter in these new solids is within a few nanometers of an interface, creating strong interplay between building blocks whose collective responses are then shaped by the long-range order of their interfacial network. In analogy to conventional atomic solids, ordering in multi-component solids with nanocrystal superlattices (NSLs) can evolve pairwise local interactions into long-range influences that couple photonic, phononic, magnetic, and electronic responses. The IRG will focus on the modular assembly of two or more types of nanostructures into a wide range of multi-component materials where a high degree of order can transform the properties of the assembly. Inter-dimensional material architectures include families of highly ordered binary nanocrystal superlattices (BNSLs) and quasicrystals, precise-number nanocrystal clusters formed by templated assembly, and the first co-crystallization of nanorods and nanospheres. These structural motifs accommodate a wide variety of semiconducting, metallic, phosphorescent, semimetallic, and magnetic nanocrystals, tunable in size (1-100 nm), shape (spheres, rods, cubes, 3- and 6-sided prisms), and surface functionalization.
* Partial MRSEC support