Phase Transitions in Liquid Crystalline Elastomers: A Fundamental Aspect of LCEs as Artificial Muscles

Abstract

Liquid crystalline elastomers (LeEs) are composed of low molecular weight mesogenic units tethered to a cross-linked polymer network. Because LeEs have remarkable shape-changing properties at the nematicisotropic phase transition, it has been suggested that they could serve as generic large amplitude, low frequency actuators and sensors i.e. artificial muscles. As this transition does not exist in LeEs when the mesogenic side chains are uniformly oriented, the understanding of phase transitions in LeEs emerges as a topic of fundamental interest for their application as artificial muscles.

Study of the optical, thermal, and mechanical properties of nematic liquid crystal elastomers

“…Liquid crystal elastomers (LCEs) have emerged as potential candidates for shape memory polymer due to their unique combination of interesting properties, such as the ordering property of the low-molecular-weight liquid crystal (LC) and the rubber elasticity of the polymer network [1][2][3]. The synthesis of LCE involves a two-step cross-linking process, which results in a material where mesogenic units are chemically bound to the cross-linked polymer [4].…”

Bio-Inspired Soft Robotics: Tunable Photo-Actuation Behavior of Azo Chromophore Containing Liquid Crystalline Elastomers

“…Researchers investigated a wide variety of LCEs with diverse liquid crystalline phases including nematic, cholesteric (or helical), smectic phases (smectic A, smectic C, and smectic C *), and discotic and blue phases [14][15][16][17]. These LCEs with diversified liquid crystalline phases have been recognized as potentially effective to more technology-related topics, such as adaptive varifocal micro lenses in miniature electronic devices to soft actuator components of artificial muscle along with biomedical and soft robotic applications [18][19][20][21][22]. Some of the prominently studied polymers are outlined in Figure 2.…”