Coalescence of isotropic and nematic droplets in quasi 2D liquid crystal films

Coalescence of droplets is ubiquitous in nature and modern technology. Various experimental and theoretical studies explored droplet dynamics in three dimensions (3D) and on two-dimensional (2D) solid or liquid substrates, e.g. [1-3].

Here, we demonstrate coalescence of isotropic and nematic droplets in quasi-2D liquids, viz. overheated smectic A freely suspended films. We investigated their dynamics experimentally and measured the shape deformation during the entire merging process using high-speed imaging and interferometry. This system is a unique example where the lubrication approximation can be directly applied, and the smectic membrane plays the role of a precursor film. Our studies reveal the scaling laws of the coalescence time depending on the droplet size and the material parameters. We also compared the dynamics of isotropic and nematic droplets and additionally analyzed the results based on an existing model for liquid lens coalescence on liquid and solid surfaces [4].

References:

[1] J. D. Paulsen et al., Nat. Commun., 5, 3182 (2014)

[2] D. G. A. L. Aarts et al., Phys. Rev. Lett., 95, 164503 (2005).

[3] N. S. Shuravin et al., Phys. Rev. E, 99, 062702 (2019)

[4] C. Klopp et al., Langmuir, 36, 10615 (2020)