Helical pitch and thickness-dependent opto-mechanical response in cholesteric liquid crystal elastomers

Area of Science:

• Materials Science
• Optics
• Polymer Science

Background:

• Cholesteric liquid crystalline elastomers (CLCEs) are known for their selective reflection and deformability.
• Previous studies noted that CLCEs with long pitch lengths do not exhibit total reflection upon deformation.

Purpose of the Study:

• To systematically investigate the opto-mechanical response of CLCEs across the electromagnetic spectrum (visible to MWIR).
• To determine the factors governing total reflection in CLCEs, specifically the role of pitch length and thickness.

Main Methods:

• Preparation of CLCEs with tunable selective reflection.
• Optical characterization using polarized optical microscopy (POM), UV-vis, and FTIR spectroscopy.
• X-ray scattering to analyze mechanical origins.

Main Results:

• Established that total reflection in CLCEs is dependent on the number of helical pitches (Np).
• Demonstrated CLCEs with selective reflection spanning visible to mid-wave infrared (MWIR).
• Uncovered the mechanical origins of optical properties through combined characterization techniques.

Conclusions:

• The number of helical pitches is critical for achieving total reflection in CLCEs.
• Tunable and reversible optical properties make CLCEs suitable for advanced photonic devices.
• CLCEs show promise for adaptive optics, sensors, tunable reflectors, and reconfigurable photonic devices.