Homogeneous Alignment of Liquid Crystalline Dendrimers Confined in a Slit-Pore: Computational Simulation Study

TL;DR

This study uses Monte Carlo simulations to explore how liquid crystalline dendrimers align within a slit-pore under different pressures, revealing surface-induced order and decay of alignment with distance from the substrate.

Contribution

It provides detailed computational insights into the conformational and alignment behavior of LC dendrimers confined in slit-pores, highlighting pressure-dependent alignment decay and layered structures.

Findings

Surface anchoring induces strong local alignment at low pressure.

Alignment decays with distance from the substrate as pressure increases.

Layered smectic-like structures form near the confining walls.

Abstract

In this work we present results from NPT(isobaric-isothermal) Monte Carlo Simulation studies of Liquid Crystalline Dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. We investigate the substrate induced conformational and alignment properties of the system at different thermodynamic state points under uniform (unidirectional) anchoring condition. Tractable coarse grained force fields to model both monomer-monomer and monomer-substrate interaction potentials have been used from our previous work. In this anchoring condition, at lower pressure almost all the monomers are anchored to the substrates and mesogens are perfectly aligned with the aligning direction. This alignment is not uniformly transmitted to the bulk region as the pressure grows, instead, it decays with distance from the surface to the bulk region. Due to this reason, the global orintational order parameter decreases with increasing pressure (density). In the neighborhood (2-3 mesogenic diameter) of upper and lower walls, mesogenic units form smectic A like structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.