Confinement effect on the interaction between colloidal particles in a nematic liquid crystal: an analytical study

Area of Science:

• Soft Matter Physics
• Colloidal Science
• Liquid Crystal Physics

Background:

• Recent experiments investigated interactions between colloidal particles within confined nematic liquid crystals.
• Understanding these interactions is crucial for predicting colloidal behavior in confined environments.

Purpose of the Study:

• To analytically determine the interaction potential (U) between spherical colloidal particles in a confined nematic cell.
• To characterize how the potential varies with interparticle distance (r) and cell thickness (d).

Main Methods:

• Analytical modeling of interparticle forces.
• Mathematical derivation of the interaction potential as a function of interparticle distance and cell thickness.

Main Results:

• The short-range interaction potential follows a power law, U(r) ~ r^(-5), consistent with quadrupolar interactions.
• The long-range potential is dominated by an exponential function, U(r) ~ sqrt(d/r) * exp(-2*pi*r/d).
• The transition between these two regimes occurs at an interparticle distance to cell thickness ratio of approximately 0.8.

Conclusions:

• The derived analytical model provides a semiquantitative explanation for the experimentally observed interaction potentials.
• The study elucidates the distinct short-range and long-range behaviors governing colloidal interactions in confined nematic liquid crystals.