Low-voltage-driven electromechanical effects of swollen liquid-crystal elastomers

Area of Science:

• Materials Science
• Polymer Science
• Soft Matter Physics

Background:

• Liquid-crystal elastomers (LCEs) exhibit unique electromechanical properties.
• Low-molecular-weight liquid crystals (LMWLCs) can be used to modify LCE behavior.

Purpose of the Study:

• To experimentally investigate the electromechanical effects in LCEs swollen with LMWLCs.
• To quantify the impact of swelling on the threshold electric field and response times.

Main Methods:

• Swelling of polydomain (POLY) and monodomain (MONO) LCEs with 4-n-pentyl-4-cyanobiphenyl (5CB).
• Measurement of shape changes under varying voltages and temperatures.
• Analysis of response and relaxation times in relation to electric field strength.

Main Results:

• Measurable shape changes (1-20 microm) observed with low voltages (0.5-10 V) across a 100 microm gap.
• A ~200-fold decrease in the threshold electric field for electromechanical effects in swollen LCEs compared to unswollen LCEs.
• Response time dependence on the electric field (E^2) similar to LMWLCs, while relaxation time showed distinct behavior attributed to the LCE network.

Conclusions:

• Swelling LCEs with LMWLCs dramatically enhances their electromechanical response, significantly lowering the required electric field.
• The observed phenomena provide insights into the interplay between LCE network dynamics and LMWLC behavior under electric fields.
• This study highlights the potential of swollen LCEs for applications requiring sensitive electromechanical actuation.