Transforming patterned defects into dynamic poly-regional topographies in liquid crystal oligomers

Area of Science:

• Materials Science
• Soft Matter Physics
• Nanotechnology

Background:

• Dynamic surface topographies are crucial for advanced material functionalities.
• Existing methods for creating surface textures often lack dynamic control or sufficient amplitude.
• Liquid crystal networks (LCNs) offer potential for stimuli-responsive materials but require further development for complex topography.

Purpose of the Study:

• To create high-aspect-ratio dynamic poly-regional surface topographies using main-chain liquid crystal oligomer networks (LCONs).
• To investigate the formation and characteristics of these topographies triggered by heat and light.
• To explore the potential applications of these tunable surfaces.

Main Methods:

• Photopatterning of alignment layers to control director patterns and topological defects in LCON coatings.
• Activation of defect regions using heat and/or light irradiation (including azobenzene moieties for light-responsiveness).
• Finite Element Method (FEM) modeling to simulate topography formation and understand stress relaxation mechanisms.

Main Results:

• Formation of reversible, dynamic surface topographies with features like protrusions, ridges, and valleys at topological defects.
• Achieved a large modulation amplitude of approximately 60%, significantly exceeding that of conventional LCNs.
• Demonstrated erasure of topographies upon cooling or blue light irradiation, returning the surface to a flat state.

Conclusions:

• LCONs can be engineered to generate complex, dynamic surface topographies with significant amplitude.
• The developed system offers precise control over surface texture formation and erasure via external stimuli.
• These dynamic surfaces hold promise for applications in haptics, cell growth control, and intelligent surfaces with tunable adhesion and tribology.