Mechanical frustration and spontaneous polygonal folding in active nematic sheets

Area of Science:

• Materials Science
• Physics
• Soft Matter Physics

Background:

• Nematic materials exhibit unique properties due to their ordered molecular structure.
• Twisted director configurations in nematic disks can lead to complex mechanical responses.
• External stimuli like light and heat can induce significant changes in nematic materials.

Purpose of the Study:

• To investigate the bending behavior of a solid nematic disk with a specific director twist.
• To understand the relationship between geometric frustration and the resulting mechanical response.
• To identify the factors controlling the formation of curl lobes.

Main Methods:

• Analysis of the mechanical response of a solid nematic disk.
• Modeling the director configuration from radial (top) to azimuthal (bottom).
• Investigating the effects of light or heat as external stimuli.

Main Results:

• The study identifies distinct curl lobes in the nematic disk's bending response.
• The number and characteristics of these curl lobes are determined by the material's geometry.
• Mechanical frustration arising from the twisted director configuration is the primary driver of the observed bending patterns.

Conclusions:

• The geometric configuration of a nematic disk dictates its bending response to external stimuli.
• Mechanical frustration is a key factor in generating complex deformation patterns like curl lobes.
• This research provides insights into the fundamental physics of twisted nematic materials.