ChBE Seminar Series: Peering into the world of nano- and microscale assembly
Speaker: Taylor Woehl, ChBE Assistant Professor, University of Maryland
Title: Peering into the world of nano- and microscale assembly
The assembly of atomic, molecular, and colloidal building blocks into micro- and macroscopic functional structures is ubiquitous across a range of technologies and chemical processes. Materials as simple as paint rely on assembly of microparticles to form dense protective barriers, while atomic and nanoscale metallic catalysts rely on precise assembly of atoms into active catalyst sites. Emerging technologies like electronic paper and electronic windows use electric fields to manipulate micro and nanoscopic particles to produce color change and images, while state of the art LED displays utilize precisely synthesized semiconductor nanoparticles to produce bright and vivid colors. Fundamental understanding of the transport, kinetics, and chemistry involved in the assembly of these material and chemical systems has played a key role in enabling these technologies and will continue to revolutionize their properties and performance. A major focus of Dr. Woehl’s lab is to apply advanced microscopy techniques and empirical quantitative observations to derive fundamental understanding of diverse micro- and nanoscale assembly processes. The first part of the seminar will focus on using high resolution electron microscopy and radiation chemistry to elucidate the chemical processes during metal nanocrystal synthesis in the liquid phase. The work will demonstrate that a deep understanding of radiation chemistry enables quantifying nucleation and growth kinetics and reaction intermediates of mono- and multimetallic metal nanoparticles. The second part of the seminar will focus on elucidating electrohydrodynamic fluid flows that cause assembly and aggregation of nano- and microparticles. Direct microscopic observations and modeling demonstrate that EHD flows cause particles to undergo aggregation during electrophoretic deposition and exhibit reversible assembly in pH gradients. The seminar will conclude with recent studies of chemically fueled assembly of colloids and soft matter systems inspired by non-equilibrium assembly in biological systems. He will show how chemical reaction cycles can be used to build transient micro- and macroscopic materials and will present fundamental studies of the interparticle interactions controlling assembly.
Dr. Woehl obtained his Ph.D. in Chemical Engineering from University of California, Davis in 2013 and focused on in-situ electron microscopy in liquids and electrokinetic aggregation of colloids. He was an Assistant Research Scientist at Ames Laboratory from 2013-2014, where he worked on biomineralization and protein templated biomimetic nanomaterials. He was an NRC postdoctoral fellowship from 2014-2016 in the Material Measurement Lab at the National Institute of Standards and Technology, where he worked on low voltage transmission electron and ion microscopy. Dr. Woehl joined the Department of Chemical and Biomolecular Engineering at University of Maryland, College Park in 2016 as an assistant professor and holds affiliate appointments in the Department of Materials Science and Department of Chemistry & Biochemistry. He was the recent recipient of the NSF CAREER award and the ACS PRF doctoral new investigator award. Dr. Woehl leads the Nanoscale Assembly and Electron Microscopy Lab, which focuses on topics including nanochemistry of multicomponent nanocrystal formation, chemically fueled assembly of soft matter, colloidal electrokinetics, and protein aggregation.