Ionic Liquid-Doped Blue Phase Liquid Crystal Elastomer and Its Electric Field Response

Area of Science:

• Materials Science
• Polymer Chemistry
• Optoelectronics

Background:

• Blue phase liquid crystal elastomers (BPLCEs) offer flexibility and 3D optical properties for optoelectronics.
• Limited research exists on the electro-responsive characteristics of BPLCEs.
• Ionic liquids (IL) can be incorporated to modify material properties.

Purpose of the Study:

• To fabricate electro-responsive BPLCEs by introducing ionic liquid (IL).
• To investigate the influence of IL doping concentration on BPLCE self-assembly and electro-responsive performance.
• To explore the potential of IL-doped BPLCEs for flexible optoelectronic applications, especially at low temperatures.

Main Methods:

• Fabrication of BPLCEs with varying concentrations of ionic liquid.
• Systematic investigation of self-assembly behavior using optical microscopy and structural analysis.
• Characterization of electro-responsive performance under an alternating current electric field.
• Measurement of thermal properties, including glass transition temperature (Tg) and fracture elongation.

Main Results:

• Optimal IL doping concentration (2-3.5 mg/100 mg) promotes uniform BPI phase formation.
• Low IL concentration (<2 mg/100 mg) facilitates BPII → BPI transition; excessive doping (>3.5 mg/100 mg) disrupts order.
• The optimal system exhibits excellent optical quality, a low Tg of -28.78 °C, and high fracture elongation (97.6%).
• The doped BPLCE shows a lower response voltage and unique wavelength shifts (red then blue) under an electric field.

Conclusions:

• Ionic liquid doping is an effective strategy to tune the self-assembly and electro-responsive properties of BPLCEs.
• The developed BPLCEs demonstrate robust performance in cryogenic environments, expanding their application scope.
• The observed electro-optic response provides novel design pathways for advanced flexible optoelectronic devices.