CBE Seminar Series: Shu Yang

Description

Diverse and Unique Droplets Assembled from Liquid Crystalline Oligomers for Shape Morphing

Abstract: Nature provided us diverse examples of microparticles that have unique surface textures comprised of spikes, stripes, and holes as seen on fungal spores, pollen grains and insect cuticles. Further, shape transformation from one state to another is not uncommon in biology. In my talk, I will present several examples of diverse and unique droplets assembled from liquid crystal oligomers (LCOs) using a microfluidic device, where polydispersity of the chain lengths is a feature. For example, spherical LCO drops can undergo dramatic shape transition to a rich variety of non-spherical morphologies with unique internal structures upon cooling from the isotropic state to the nematic state, where molecular heterogeneity promotes and stabilize the reversible transitions. Robust, tunable, pollen-like surface patterns are formed as a result of phase separation of LCOs at the interface of the oil-in-water droplet, facilitated by the mechanical coupling of LCOs of different chain lengths at the droplet interface. When shape changing liquid crystal elastomer (LCE) microparticles synthesized from LCOs are spatially encoded in a conventional elastomer film, we realize complex shape morphing that may not be convenient or possible in LCE films by themselves. Further, when placing the discrete, shape changing LCE microparticles in a lattice, we can reconfigure the lattice from a right-handed chiral state to achiral one, then to a left-handed chiral state, without breaking the translational symmetry.

Biography: Shu Yang is a Joseph Bordogna Professor of Engineering and Applied Science, Chair of the Department of Materials Science & Engineering, and Professor of Chemical & Biomolecular Engineering at University of Pennsylvania. Her group is interested in synthesis, fabrication, and assembly of soft matter; dynamic tuning of their sizes, shapes and assembled structures, and use geometry to create highly flexible, super-conformable, and shape changing materials. Yang received her B.S. degree from Fudan University, and Ph. D. degree from Cornell University with Chris Ober. She received George H. Heilmeier Faculty Award for Excellence in Research from Penn Engineering and was selected as one of the world’s top 100 young innovators under age of 35 by MIT's Technology Review. She is a Fellow of Materials Research Society (MRS), American Chemical Society (ACS), American Physical Society (APS), and National Academy of Inventors.