Elastocapillary Driven Assembly of Particles at Free-Standing Smectic‑A Films

Colloidal
particles at complex fluid interfaces and within films
assemble to form ordered structures with high degrees of symmetry
via interactions that include capillarity, elasticity, and other fields
like electrostatic charge. Here we study microparticle interactions
within free-standing smectic-A films, in which the elasticity arising
from the director field distortion and capillary interactions arising
from interface deformation compete to direct the assembly of motile
particles. New colloidal assemblies and patterns, ranging from 1D
chains to 2D aggregates, sensitive to the initial wetting conditions
of particles at the smectic film, are reported. This work paves the
way to exploiting LC interfaces as a means to direct spontaneously
formed, reconfigurable, and optically active materials.