(2019) Predicting Surface Diffusion from Molecular Structures

Many kinds of materials, including thin films, are created by adding atoms or molecules to a surface. As a result, understanding how molecules move along a surface is an important part of making new materials. In general, diffusion and crystal growth are much faster on the surface of glasses than in the interior. How much faster depends on how big the molecules are, and how many hydrogen bonds the surface molecule has to the bulk, as MRSEC researchers have recently discovered. This model works for many different molecules, giving a quick and easy way to predict surface motion and guide the synthesis of new materials.

(2019) Mechanical Properties of Structure-TunableVapor-Deposited TPD Glass

Creating glassy thin films of organic molecules at different temperatures changes both their stability in the glassy state – their density, and how hard they are to melt – and it changes how the molecules in the films are arranged – whether they tend to lie down flat on the surface or stand straight up. Wisconsin MRSEC researchers have shown that these changes in stability and average molecular orientation also change the mechanical properties of the film, including how stiff it is and how hard it is.

(2018) Seed: Synthetic soft matter created and inspired by communal behaviors of bacteria

This Seed project engaged underrepresented minority students in STEM through the MRSEC-sponsored summer REU program at UW-Madison. Doris A. Vargas Valentin, an undergraduate student from the University of Puerto Rico—Mayaguez, learned how to use dynamic light scattering and surface and surface tensiometry to characterize the self-assembly of smallmolecule amphiphiles in solution, analyze her experimental results, and present the results of her work in a formal setting during an eight-week stay in Madison. This experience also provided opportunities for Benjamin J. Ortiz, a senior graduate student who is also an underrepresented minority student in the Wisconsin MRSEC, to develop and hone his mentoring skills.

(2018) Seed: Synthetic soft matter created and inspired by communal behaviors of bacteria

Many bacteria have evolved dynamic networks of amphiphilic molecules that form a chemical “language” that they use to communicate and regulate group behaviors. This communication, in turn, governs the synthesis of bacterial biofilms and the production of other chemical goods, including other amphiphilic or redoxactive species, that are unique to large groups or communities of bacteria typically associated with bacterial infections. Researchers at the Wisconsin MRSEC are investigating the self-assembly of this chemical alphabet, and the properties of the nanostructures that form in solution and at interfaces, to design new types of synthetic and responsive soft materials that can respond to or “communicate” selectively with bacterial communities in ways that are distinct from those of existing materials, which are generally designed to interact with or kill individual bacterial cells.

(2018) Electronic structure of thermoelectric Heusler compounds

Heusler compounds are a promising class of thermoelectric materials that can convert waste heat into electricity. Importantly, they are composed of Earth-abundant elements. Their efficiency depends sensitively on electronic structure, however, challenges in preparing high quality single crystalline samples have inhibited such measurements. Now, as part of a SEED project within the Wisconsin MRSEC, scientists have directly measured the electronic structure of high electron mobility (500 cm2/Vs) FeVSb thin films, using angle-resolved photoemission spectroscopy (ARPES). Surprisingly, the valence band of this
material is narrower and the effective mass is higher than predicted by density functional theory calculations. These results call for a re-examination of our understanding of the electronic structure in these materials, and in particular, the potential role of electron-electron correlations.

(2018) Impact of the Wisconsin MRSEC Shared Instrumentation Facilities

The Share Instrumentation Facilities of the Wisconsin MRSEC provide access to and training on over 100 state-of-the-art instruments for fabrication and characterization of m materials. They are widely used by University of Wisconsin students and staff, researchers from other universities, and representatives of companies throughout the region.

(2018) Machine Learning and Materials: Wisconsin MRSEC and the Informatics Skunkworks

The “Informatics Skunkworks” is a group dedicated to engaging undergraduates in realizing the potential of informatics for science and engineering. Skunkworks participants work together in project-based research, learning critical skills in teamwork, presentation, project management, software development, and applied data science, as well as driving data-centric approaches poised to transform the future of science and engineering. Everyone is welcome.