Two students in the Materials Science and Engineering PhD program will provide an update on their graduate research. Students in the program and students interested in learning more are welcome!

To RSVP, contact Heidi Deethardt for the meeting invitation. deethardt.1@nd.edu.

Presenters

Jizhou Jiang, Department of Chemical and Biomolecular Engineering

Title: Monitoring and controlling growth of molecular layer-by-layer assembled polyamide thin film

Abstract: Membrane processes are promising candidates with high energy efficiency, operational continuity, and cost competitiveness compared with conventional chemical separation processes. Rational membrane designs are propelled by a deeper understanding between molecular-scale membrane structure and observed transport properties. Unfortunately, the structure-property relationships are often obscured by the mesoscale heterogeneous nature of traditional organic membranes. Recently, molecular layer-by-layer (mLbL) assembly thin film has been utilized as a platform to eliminate existing ambiguity due to its advantageous tailorability and nanoscale control of the membrane architecture. A thickness-dependent performance has been reported in mLbL films composed of commonly used monomer pair, trimesoyl chloride (TMC) and m-phenylene diamine (mPD). Here, we will report the mLbL network with a tetrahedral monomer. The structure parameters during the film growth will be monitored by various high-fidelity characterization methods such as spectroscopic ellipsometry, polarized modulating infrared reflection-absorption spectroscopy, and atomic force microscopy. By comparing with the TMC-mPD monomer pair, we can elucidate the effect of monomer geometry on the dynamics of film growth. The knowledge gained will assist in constructing better membrane structures and provide insights for further monomer designs.

Yang Ding, Department of Chemistry and Biochemistry

Title: Surface chemistry of cesium lead bromide perovskite nanocrystals

Abstract: Achieving condensed phase optical refrigeration requires near-unity emission quantum yields (QYs). Colloidal CsPbBr3 nanocrystals (NCs) are promising candidates in this respect given near unity QY-values, achieved by post-synthetic surface treatment with quaternary ammonium bromide ligands. The origin of these QY enhancements, however, is not understood. Systematic nuclear magnetic resonance studies of the organic ligand passivation of near unity QY CsPbBr3 NC surfaces are therefore conducted to better reveal their surface-ligand interactions.