Ph.D. Candidate, University of Pennsylvania
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“Liquid crystallinity in responsive soft materials: embedding intelligence via anisotropy”
Liquid crystal (LC), commonly known from LC displays, is a state of fourth matter for materials that have intrinsic anisotropy as it possesses both the fluidic property of liquid and the long-range ordering of crystals. Different from responsiveness provided by soft materials with isotropic networks such as hydrogels and shape memory polymers, the intrinsic anisotropy of LCs provides a facile method to realize programmable and reversible responsiveness in soft materials.
In this talk, I will first describe how liquid crystallinity could act as a template for creating diverse surface patterns in LC elastomer (LCE) microparticles. Specifically, I will show how the biophysical pathway of pollen grain pattern formation is recapitulated through the phase separation of LC oligomers (LCOs) coupled to surface anchoring at the droplet interface.
Second, I will show fabrication of meter-long LCE composite filaments as muscle-like soft robotic actuators in response to both IR light and electrical fields via extrusion. By adding a small quantity of cellulose nanocrystals (CNCs) and carbon nanotubes (CNTs) in LCOs, we improve the LC alignment and the mechanical property of filaments, respectively, achieving high work capacity for integration into a variety of soft intelligent systems. Finally, I will discuss the assembly of cellulose nanocrystals into chiral structures for integration with responsive hydrogels. The integration between isotropic hydrogel networks and intrinsic anisotropy will potentially offer new insights to engineer next generation responsive and multi-functional soft materials.
Jiaqi Liu, Graduate Research Assistant, Ph.D. Candidate, University of Pennsylvania
Jiaqi Liu is currently a Ph.D. candidate under the guidance of Prof. Shu Yang in the Department of Materials Science and Engineering at University of Pennsylvania. She received her B.S. degree in Material Chemistry from Fudan University, China in 2016, where she graduated with honor. Her research interest lies in understanding the self-assembly of liquid crystals and applying their anisotropy and responsiveness in elastomers or hydrogels for applications such as soft actuators and biomedical uses. She received Geoffrey Belton Graduate Fellowship Award from the Department of Materials Science and Engineering, University of Pennsylvania in 2019.