Thermodynamically Anchoring-Frustrated Surface to Trigger Bulk Discontinuous Orientational Transition.

Area of Science:

• Surface science
• Materials science
• Soft matter physics

Background:

• Liquid crystal (LC) nanostructures are crucial for studying surface phenomena and technological applications.
• Understanding bulk alignment and surface anchoring is key to LC research.
• A recent study found a discontinuous bulk orientational transition in a nematic liquid crystal (NLC) on a perfluoropolymer substrate.

Purpose of the Study:

• To investigate the thermodynamic growth process of smectic liquid crystalline wetting nanosheets.
• To explain the mechanism behind the discontinuous bulk orientational transition in NLC systems.
• To provide insights into how interfacial molecular architectures influence bulk material properties.

Main Methods:

• Experimental grazing-incidence X-ray diffraction (GI-XRD) measurements.
• Free-energy analysis based on experimental data.
• Thermodynamic modeling of interfacial processes.

Main Results:

• Confirmed a thermodynamic growth process of smectic liquid crystalline wetting nanosheets on the perfluoropolymer surface.
• Identified a frustrated surface with competing planar and vertical anchoring states.
• Demonstrated that elastic energy cost associated with frustrated anchoring kinetically triggers a first-order bulk reorientation.

Conclusions:

• The observed bulk reorientation is initiated by an interfacial bottom-up process.
• Frustrated surface anchoring and elastic energy are key drivers of the discontinuous orientational transition.
• This study offers a general framework for understanding how interfacial hierarchical structures impact bulk material properties.