MSE Department Seminar

Owing to the unique interface coupling and vertical interfacial strain, vertical heteroepitaxial nanocomposite films can be used to design enhanced and/or novel functionalities. In this talk, I will discuss our efforts to design, synthesize and characterize a variety of epitaxial vertical nanocomposite thin films. Nanopillar feature size has been found to be a critical parameter to control strain, defects and vertical interface density.

EFRC WastePD (Center for Performance and Design of Nuclear Waste Forms and Containers) is a multi-institute energy frontier research center established by Department of Energy in 2016 with the key mission to understand the fundamental mechanisms of waste form performance and apply that understanding to develop tools for design of waste forms with improved performance. Key performance parameter of nuclear waste forms is degradation by interaction with aqueous environment (corrosion) over long periods of time.

Long wavelength longitudinal phonons can propagate in liquids, but whether transverse phonons exist in liquids has been debated since the 1970s. The classic hydrodynamic theory refutes the existence of the latter because the transverse current fluctuation does not directly couple with the density fluctuation and the Brillouin zone is not well-defined. However, such arguments fail to describe the viscoelastic response of liquids and glasses. Recently, we have developed a viscoelastic hydrodynamic theory by incorporating both viscoelasticity and anisotropy.

Degradable polymers are used widely in medical devices and regenerative medicine.  Maturing capabilities in additive manufacturing coupled with advances in orthogonal chemical functionalization methodologies have enabled a rapid evolution of defect specific form factors and strategies for designing and creating bioactive scaffolds.

Symmetry lies at the heart of the laws of nature and determines material properties at the fundamental level. We all know that breaking the inversion symmetry is directly mapped into materials properties by inducing a plethora of effects such as dielectric polarisation along with pyro- and ferroelectricity, piezoelectricity, bulk photovoltaic effect, electro-optic effect and second harmonic generation, etc. Material symmetry in chiefly determined by its pristine crystallographic structure, but external stimuli can also lower symmetry or even break the inversion symmetry.

Synthetic polymers are among the most important materials to modern society. The development of living and controlled polymerization methodologies have enabled the synthesis of precise macromolecular architectures with tailored polymer properties for diverse applications. This presentation will discuss the design, development, and use of organic photoredox catalysts in organocatalyzed atom transfer radical polymerization for the synthesis of well-defined polymers.

Plasmonic nanoparticles are particularly interesting as they are strongly absorbing in the near infrared (NIR) regime and their associated temperature increase is sensitively dependent on the shape and composition of the structure and on the wavelength of light. Therefore, much effort is put into synthesizing novel nanostructures for optimized interaction with incident light in the NIR regime which has a relatively long penetration depth into biological tissue.

Cold Sintering involves a transient phase that permits the densification of particulate materials at low temperatures 300^oC and below. Sintering at such low temperature offers so many new opportunities. It permits the integration of metastable materials that would typically decompose at high temperatures. So cold sinter enables a platform for better unification of material science. Now ceramics, metal and polymers can be processed under a common platform in one step processes. With controlling the forming process new nanocomposites can be fabricated.

Due to their high specific strength, carbon and glass fiber reinforced composites find wide applications as lightweight and high strength materials, for aerospace and automotive applications. However, these composite materials are extremely sensitive to relatively low velocity, and localized impact loads leading to damage in the through thickness direction. The mechanical damage induces delamination (separation cracks) at the boundary between plies. Delamination due to crack growth is one of the most prevalent life-limiting factors of a composite.

Materials prediction is the ultimate solution for ending blind experimental search within an
expansive material parameter space. First-principles theory entirely based on quantum mechanics
without prior input parameters is the perfect tool for new material design. In order to predict exotic
quantum materials and out-of-equilibrium processes, many-body physics and quantum kinetic theory are
needed to bridge with first-principles methods.