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Program Highlights

Structural Chemo-Mechanics of Fibrous Networks

Research

Shenoy group in the IRG led a study on the multiaxial behavior of collagen networks. When stretched, the network models exhibited drastic contractions transverse to the direction of loading (yellow arrows in the top left image). The networks exhibited an anomalous Poisson effect, with apparent Poisson’s ratios larger than 1. Experiments validated this result and showed increases of apparent Poisson’s ratio with decreasing collagen concentration (top right image).

(2019)

Machine Learning & Softness: Characterizing local structure and rearrangements in disordered solids

Research

This IRG focuses on the mechanical behavior of disordered materials, particularly beyond the onset of yield. The Figure shows recent advances in using Machine Learning (ML) methods to characterize the local structural environment of disordered materials with respect to susceptibility for particulate rearrangements using a quantity called softness. (A-D) shows an analysis of a polycrystalline material (created via Molecular Dynamic simulations) using ML and the concept of softness [1]. The Figure shows that softness (bright spots in D) is able to capture rearrangements measured as shown by colored particles in (C). This approach correctly identifies crystalline and grain boundary regions as having low values and high variability of softness, respectively. We also extended the concept of softness to anisotropic particles [2] (E). Similar predictive performance to isotropic particles is observed and a recursive feature elimination (RFE) method is introduced to better understand how softness arises from particular structural aspects that can be systematically tuned e.g. by particle aspect ratio.  Indeed, longer particles lead to different global flow patterns for a pillar under compression (F).

(2019)

Network Analysis of Synthesizable Materials Discovery

Materials synthesis is a complex process that depends not only on thermodynamic stability, but also on kinetic factors, advances in synthesis techniques, and the availability of precursors. This complexity makes the development of a general theory for predicting synthesizability extremely difficult.

(2019)

Improving the Ambient Stability of Chemically Reactive 2D Materials

To enable ambient processing and study of indium selenide, NU-MRSEC IRG-1 has developed a mixed-dimensional organic/inorganic passivation scheme based on n-methyl-2-pyrrilodone (NMP) seeded atomic layer deposited (ALD) alumina that provides a pinhole-free encapsulation layer that preserves the intrinsic electronic properties of the underlying InSe.

(2019)

Optically Reconfigurable Dielectrics in Ultra-Thin Transistors

In this work, molecular self-assembly of highly polarizable PAE molecules was used to create reconfigurable dielectric layers whose capacitance changes with illumination. Upon ultraviolet optical illumination, the PAE molecules undergo a photoisomerization from an extended trans geometry to a compact cis geometry, which can be reversed upon illumination at longer wavelengths.

(2019)

Reaching Underserved Audiences by Bringing Science to a Local Food Pantry

Not all members of our community have the time or resources to attend science outreach events. To reach some of those people, the Wisconsin MRSEC conducts its engaging, hands-on science activities to a local food pantry. Customers can wait up to 90 minutes at the food pantry, providing ample time for educational activities for kids, their parents, and other curious adult visitors.

(2019)

Nanoscale Control of Complex Oxide Crystallization

Small (nanometer-sized) crystals of multi-component, complex metal oxides have useful properties for applications in electronics, optics, sensors, and mechanical actuators. In order to realize this potential, engineers need to be able to put tiny crystals exactly where they are needed and to control the orientation of the crystal’s lattice.

(2019)

Optical Excited States in a Moiré Crystal

In transition metal dichalcogenides (TMDC) monolayers, there are two inequivalent valleys (energy extrema points in the band structure) related by time-reversal symmetry. Fundamental optical excitations, or excitons (bound electron-hole pairs) are formed at these valleys.

(2019)

Gelation of Plasmonic Metal Oxide Nanocrystals by Polymer-Induced Depletion Attractions

Nanocrystal gelation is a strategy to translate exceptional properties inherent to nanoscale building blocks into multiscale architectures and devices. However, available gelation methods are not easily adaptable across broad classes of nanocrystal systems since assembly is strongly reliant on specific surface chemistries.

(2019)

Musical Magnetism: Engaging Middle School Students in Materials Science

Education

The Illinois MRSEC developed and implemented an 8-week program called “Musical Magnetism” that engages middle school students in materials science using the popular platform of music. The program combines engaging lessons and demos, researching a topic, turning that research into lyrics, and recording a song. 35 8th graders at Franklin STEAM Academy participated.

(2019)

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