28th International Liquid Crystal Conference (ILCC2020)


Structures with helical shape are commonly found in nature at many scales, ranging from plant tendrils to molecules. Many organisms take advantage of the helical shape to fold, propel and assemble in a “smart” way. For instance, the flowering plant Erodium uses a peculiar mechanism for seed dispersal. Seeds have the capability of drilling in the ground by undertaking several cycles of winding and unwinding. In animals, the cuticula of some beetles exhibits an iridescent cholesteric structure with a selective reflection of left circularly polarised (LCP) light and transmission of right circularly polarised (RCP) light. Inspired by how helicity arises in nature, we investigated the mechanisms ruling the shaping of helical assembled structures: humidity-responsive parts of Erodium awns were isolated and tuned, in which the chemical treatment inverts the handedness typically observed; responses to both LCP and RCP light were obtained in the same solid films from cellulose derivative cholesteric liquid crystalline solutions in the presence of a reactive solvent. These results can find potential applications in micro and nanorobotics, soft-electronics and nanophotonics.

Faculty of Sciences of the University of Lisbon
Lisbon, Portugal