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Liquid crystal elastomer shells with a negative order parameter ground state

Tuesday, February 27, 2018 - 3:30pm - 4:20pm
Lind 305
Jan Lagerwall (University of Luxembourg)
While more and more research groups around the world explore liquid crystal elastomers (LCEs) as soft actuators, for use in, e.g., soft robotics, most experimental approaches produce LCEs that are flat films in their ground state, and they all have positive order parameter in the liquid crystalline phase. Using capillary microfluidics we produce shells of a liquid crystal elastomer precursor, which is turned into a hollow spherical LCE via a two-stage polymerization and crosslinking procedure, with an intermediate osmotic stretching step. Interestingly, this procedure does not just give rise to unconventional shapes with spherical topology (also tubes can be made by modfying the procedure), but the LCE turns out to have a negative order parameter ground state. We explain why our procedure gives rise to this highly elusive LCE configuration, and discuss the actuation of LCEs that break the conventional norms in terms of shape as well as type of internal ordering.