Lecture Series: When Soft Materials Meet Electron Microscopy

An overview from Professor Qian Chen

Prof. Qian Chen
In this ICAM webinar, Professor Qian Chen from the University of Illinois at Urbana-Champaign discussed three soft materials systems whose nanoscale structure and dynamics, conventionally difficult to resolve, dictate their function.
 
The first system concerned the elusive nucleation pathways of crystals at the nanoscale. We are able to directly image the full crystallization of nanoparticles using liquid-phase transmission electron microscopy (TEM). Single-particle tracking, when combined with Monte Carlo simulation techniques, reveals a series of unexpected crystallization pathways for different nanoparticle shapes due to the inherent many-body coupling and discreteness at the nanoscale.
 
The second system concerned organic materials, polymeric films synthesized from interfacial polymerization but exhibit nanoscopic three-dimensional (3D) morphology. We image and reconstruct the 3D morphology using electron tomography. Our morphometry analysis reveals a crumpling mechanism in the film’s morphology development. The film’s morphology also has intricate indications on their applications in water filtration, particularly solvent permeation and solute retention.
 
The third system pushes further the boundaries of liquid-phase TEM to single biomolecules. Through extensive technological advancements, we capture the first TEM movies of membrane proteins fluctuating and rotating in their native buffer. All systems work together to achieve our common goal of deciphering fundamental rules of organization from “seeing is believing”, enabled at the emergent interfacing of soft materials and advanced electron microscopy.
 
Professor Qian Chen received her B.S. in Chemistry from Peking University, China (2007), and her PhD in Materials Science and Engineering from the University of Illinois at Urbana-Champaign with Professor Steve Granick (2012). Her doctoral research focused on developing new “bottom-up” strategies for materials construction. She was among the first to encode multiplexed information into colloids in a “Janus” or “patchy” fashion, and to assemble them into functional materials. She found these materials exhibit properties that were new and exciting to the community, including “supracolloidal” reactivity and entropic stabilization of ordering. In 2012, Professor Chen obtained a Miller postdoc fellowship and worked with Professor Paul Alivisatos at UC Berkeley. There she explored broadly structural and functional dynamics at nanoscale, including liquid phase TEM and plasmonics based bio-sensing. She pioneered the efforts in unprecedented in situ imaging of biomolecular transformation at nm resolution, and the spatial mapping of nanoscale interactions among colloidal nanocrystals.
 
In 2015, Professor Chen joined the faculty of the University of Illinois at Urbana-Champaign as Assistant Professor of Materials Science and Engineering and Affiliate of the Department of Chemistry. In 2016, she was listed on the Forbes 30 under 30 science list and named one of Science News Magazine’s ‘10 scientists to watch’. In 2018, Professor Chen was awarded an Alfred P. Sloan Research Fellowship in Chemistry and the Unilever award by the American Chemical Society (ACS).