Shape instabilities of islands in smectic films under lateral compression

Amine Missaoui (1, 2) , Kirsten Harth (1) , Torsten Trittel (1) , Christoph Klopp (1) , Ralf Stannarius (1) , Emmanuelle Lacaze (2)

1 OVGU - Otto-von-Guericke-Universität Magdeburg = Otto-von-Guericke University [Magdeburg]
2 INSP-E6 - Physico-chimie et dynamique des surfaces

Smectic liquid crystals are fluids, and in most rheological situations they behave as such. Nevertheless, when thin freely floating films of smectic A or smectic C materials are compressed quickly in-plane, they resist such stress by buckling similar to solid membranes under lateral stress. We report experimental observations of wrinkling and bulging of finite domains within the films, so-called islands, and give a qualitative explanation of different observed patterns. Depending on the external stress and their dimensions, the islands can expel a specifically shaped bulge in their center, form radial wrinkles or develop target-like wrinkle structures. When the external stress is relaxed, these patterns disappear reversibly.

Domaines: Physique [physics]

Amine Missaoui, Kirsten Harth, Torsten Trittel, Christoph Klopp, Ralf Stannarius, et al.. Shape instabilities of islands in smectic films under lateral compression. Soft Matter, 2022, 18 (16), pp.3193-3205. ⟨10.1039/d2sm00144f⟩. ⟨hal-03713549⟩