Encoding Gaussian curvature in glassy and elastomeric liquid crystal solids.

Area of Science:

• Materials Science
• Soft Matter Physics
• Geometry

Background:

• Thin, solid nematic sheets possess unique properties for programmable shape morphing.
• Preprogrammed director fields can induce local deformations and control surface geometry.
• Stimuli-responsive materials offer pathways for dynamic shape control.

Purpose of the Study:

• To describe and analyze shape transitions in nematic sheets with patterned director fields.
• To investigate the intrinsic geometry, specifically Gaussian curvature, of morphing surfaces.
• To present experimental validation of theoretical predictions for programmed solids.

Main Methods:

• Utilized a metric description of local deformations to study intrinsic surface geometry.
• Designed specific director field patterns to encode constant Gaussian curvature.
• Conducted experiments exposing nematic sheets to light and heat stimuli.

Main Results:

• Demonstrated shape transitions from flat sheets to surfaces with controlled positive and negative Gaussian curvature.
• Logarithmic spiral patterns generated cone/anti-cone surfaces; spiral fields created punctured disc geometries.
• Experimental results qualitatively supported theoretical predictions for photomechanical morphing.

Conclusions:

• Programmed nematic solids offer a route to creating complex, stimulus-responsive surfaces.
• Conditions for anchoring these responsive regions in substrates were derived for device integration.
• The study paves the way for exploiting these materials in novel devices and applications.