Kathleen J. Stebe Department of Chemical and Biomolecular Engineering University of Pennsylvania USA

Active colloidal particles in nematics for reconfigurable materials and microrobotics.

Active colloidal particles in nematic liquid crystals (NLC) provide diverse routes for materials manipulation. The particles’ shape and surface chemistry can be tailored to generate companion topological defects. The particles’ motion can drive far-from-equilibrium defect dynamics that generate new modes of motion and nemato-elastic interactions. We develop active colloidal systems that embed and dynamically reconfigure information in their nematic liquid crystalline milieu, generating a suite of interactions for manipulation of passive colloidal building blocks or colloidal cargo. Since these interactions rely on the colloidal cargo surface chemistry and not its material composition, the interactions can be used to build and reconfigure structures from diverse colloidal building blocks at multistable sites in the domain. Furthermore, these experiments generate open fundamental questions regarding driven colloid behavior, including swimming in NLC, the generation of work from stored nemato-elastic energy, and the dynamics and pinning of topological defects.