Rupture and recoil of bent-core liquid crystal filaments

Abstract

The recoil process of free-standing liquid crystal filaments is investigated experimentally and theoretically. We focus on two aspects, the contraction speed of the filament and a spontaneously formed undulation instability. At the moment of rupture, the filaments buckle similarly to the classical Euler buckling of elastic rods. The tip velocity decays with decreasing filament length. The wavelength of buckling affinely decreases with the retracting filament tip. The energy gain related to the decrease of the total length and surface area of the filaments is mainly dissipated by layer rearrangements during thickening of the fibre. A flow back into the meniscus is relevant only in the final stage of the recoil process. We introduce a model for the quantitative description of the filament retraction speed. The dynamics of this recoil behaviour may find relevance as a model for biology-related filaments.

Coalescence of Islands in Freely-Suspended Smectic Films

“…To move in and out of the boundary region of a merging island domain, molecules need to permeate between layers, a process which dissipates more energy than purely 2D flow confined within the layers. Analogous effects of permeation at the highly dislocated bounding meniscus of freely suspended films have been reported previously in a variety of studies [45][46][47][48]. In our experiments, as coalescence progresses the domain boundary gets shorter, at a rate limited by how fast the liquid crystal molecules can escape from the shrinking boundary region.…”

Physics of liquid crystals of bent-shaped molecules

“…Magdeburg, Germany (Biscari and Calderer 2005;Bauman and Phillips 2009) and Kent, Ohio(Antal Jákli, Krüerke, and Nair 2003;T. Ostapenko et al 2014;Salili, Ostapenko, et al 2016) providing information on filament tensions and damping processes (Martin W. Schroder Gerhard Pelzl, and Wolfgang Weissflog 2004;Yao, Spiegelberg, and McKinley 2000;Stannarius, Nemeş, and Eremin 2005;Nemeş 2008;Nemeş et al 2006;Nemes, Eremin, and Stannarius 2006;Petzold et al 2009;Antal Jákli, Krüerke, and Nair 2003;Coleman et al 2003). A transition between the disc-shaped and cone-shaped configurations gives rise to a new relaxation soft mode, where the direction of the cone tip oscillates.…”

Dynamic wrinkling of freely floating smectic films

“…The formation of wrinkles of fluid interfaces have also been described during the impact of droplets onto a viscous liquid [13] and for droplets rising in a liquid [14]. A related phenomenon is the buckling of viscous fluid filaments [15,16].…”