Light-activated helical inversion in cholesteric liquid crystal microdroplets

Piotr Sleczkowski, Ye Zhou, Supitchaya Iamsaard, Juan J. De Pablo* (Corresponding Author), Nathalie Katsonis (Corresponding Author), Emmanuelle Lacaze (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

18 Citations (Scopus)
44 Downloads (Pure)

Abstract

Cholesteric liquid crystal (CLC) droplets exhibit nontrivial topological features, which are controlled by the ratio between the cholesteric pitch and the droplet radius. The radial spherical structure (RSS) is of particular interest, as it reveals an onion-like concentric organization of the cholesteric helices, leading to the expression of spherical Bragg microcavities. Using an overcrowded alkene-based unidirectional molecular motor as a dopant, we show that the topological defect structure in the droplet can be activated by illumination. By using appropriate molecular motor concentrations, light can either break the symmetry of topological defects (as observed for the bent-twisted bipolar structure), or it can induce inversion of handedness in an onion-like organization (in the case of RSS). This latter feature may pave the way toward alternative activation modes of lasers based on cholesteric droplets. By also studying CLC droplets once they have reached full photoconversion at photostationary state (PSS), we highlight that the strong influence of confinement on the droplets structure occurs to the same extent after the helix inversion event. Our results are interpreted in terms of numerical simulations of the droplets’ structure, which shed light on the major role played by curvature close to the droplets’ center, this latter one becoming dominant when the droplet radius is small.

Original languageEnglish
Pages (from-to)4334-4339
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number17
DOIs
Publication statusPublished - 24 Apr 2018

Keywords

  • Chiral liquid crystals
  • Confinement
  • Droplets
  • Inversion
  • Molecular motors
  • Photoinduced helix

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