Twist-bend nematic drops as colloidal particles: Electric instabilities

K. S. Krishnamurthy, D. S. Shankar Rao, Santosh Y. Khatavi, and Channabasaveshwar V. Yelamaggad
Phys. Rev. E 107, 044703 – Published 28 April 2023
PDFHTMLExport Citation

Abstract

The mesogen 1,′′7′′-bis(4-cyanobiphenyl-4′-yl)heptane (CB7CB), doped with a small quantity of an amphiphilic compound, is examined in its biphasic state in which twist-bend nematic (NTB) drops are dispersed in the isotropic fluid. Various flexoelectric and electrokinetic responses of small drops in their escaped-radial-like (ER) geometry, and also of larger ones with parabolic focal conic defects, are discussed. A pair of confocal parabolas with their axes along the applied low-frequency electric field undergo periodic dimensional changes so as to contribute flexoelectrically to free-energy reduction. In an ER droplet, the same result is achieved by periodic relocations of the hedgehog core. Sine-wave fields of low frequency and high voltage excite patterned states near zero-voltage crossings and homeotropic alignment at peak voltages. ER drops also exhibit electrohydrodynamic effects; in relatively weak fields, they undergo translatory motion with a velocity that is a quadratic in the field strength; the drift, which occurs over a very wide frequency range, extending from dc to MHz region, is enabled by radial symmetry breaking that their off-centered geometry entails; and the drift direction reverses across a critical frequency. In high fields, vortical flows occurring within an ER NTB drop become discernible. The hydrodynamic effects are discussed based on the Taylor-Melcher leaky dielectric model.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
9 More
  • Received 19 January 2023
  • Accepted 10 April 2023

DOI:https://doi.org/10.1103/PhysRevE.107.044703

©2023 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft Matter

Authors & Affiliations

K. S. Krishnamurthy1,*, D. S. Shankar Rao1, Santosh Y. Khatavi1, and Channabasaveshwar V. Yelamaggad1,2

  • 1Centre for Nano and Soft Matter Sciences, Survey No. 7, Shivanapura, Bangalore 562162, India
  • 2Manipal Academy of Higher Education, Madhav Nagar, Manipal 576104, India

  • *Author to whom correspondence should be addressed: murthyksk@gmail.com

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 107, Iss. 4 — April 2023

Reuse & Permissions
Access Options

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review E

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×