Phase-field model for a weakly compressible soft layered material: morphological transitions on smectic-isotropic...

Area of Science:

• Physics
• Materials Science
• Fluid Dynamics

Background:

• Smectic liquid crystals exhibit complex phase behavior.
• Understanding morphological transitions in thin films is crucial for materials science applications.
• Existing models may not fully capture the interplay between phase transitions and hydrodynamics in smectic systems.

Purpose of the Study:

• To develop and present a novel coupled phase-field and hydrodynamic model for two-phase smectic systems.
• To investigate the morphological evolution of smectic thin films under thermal stress.
• To elucidate the mechanisms driving defect transformation and layer dynamics.

Main Methods:

• A non-conserved order parameter for the smectic phase coupled with a conserved mass density.
• Incorporation of hydrodynamic interactions and density gradients.
• Numerical simulation of the governing equations to track temporal evolution.

Main Results:

• The model accurately describes the transition of focal conic defects into conical pyramids and concentric rings.
• Curvature-dependent evaporation and non-classical boundary stresses are identified as key factors.
• Temperature increases sculpt pyramidal domains with tangential surface flows.
• Simulations also show domain coalescence, droplet formation, and defect interactions.

Conclusions:

• The coupled model provides a robust framework for studying smectic thin film dynamics.
• Density contrast and surface curvature significantly influence morphological transitions.
• The findings offer insights into controlling liquid crystal microstructures for advanced applications.