Join us for a special seminar with visiting guest speaker Yuzhan Li from the University of Science and Technology Beijing for his talk on October 25th at 10am in Maryland Hall room 109.
Abstract: Exchangeable Liquid Crystalline Elastomers: Enabling Rapid Processing and Enhanced Actuation Stability through On-Demand Deactivation
Exchangeable liquid crystalline elastomers (xLCEs) bearing dynamic covalent bonds are promising candidates for soft actuators due to their unique capability to adjust both network structure and liquid crystalline (LC) alignment after polymerization. While current xLCEs with low exchange temperatures are convenient for processing, they suffer from issues such as creep and loss of LC alignment during repeated thermal actuation. Herein, we present an effective solution using dynamic anhydride chemistry within a thiol-ene-based xLCE. This approach enables a catalyst-free, low-temperature bond exchange of the xLCE after polymerization, allowing for the adjustment of LC orientation under mild conditions. More importantly, it enables on-demand deactivation of the bond exchange via anhydride hydrolysis, effectively eliminating creep and enhancing actuation stability for over 100 cycles. Furthermore, the hydrolysis process results in the formation of carboxylic acid groups, which can be converted into carboxylates via alkali treatment, thereby providing the xLCE with humidity responsiveness. These findings highlight the use of dynamic anhydride bonds in the fabrication and optimization of xLCEs with enhanced durability and functionality, which is expected to facilitate advancements in their applications in soft actuators and robotics.
Bio: Yuzhan Li
Yuzhan Li is an Associate Professor at the Department of and Materials Science Engineering at University of Science and Technology Beijing. He received his PhD in Materials Science and Engineering from Iowa State University in 2014. Then, he worked at Washington State University as a Staff Scientist from 2014-2018 and then at Oak Ridge National Laboratory from 2018-2021. Yuzhan’s research interests are focused on the design and synthesis of liquid crystalline elastomers (LCEs). His current and previous studies involve the development of LCEs with improved actuation performance using orthogonal click chemistries and controllable dynamic covalent bonds.