Nanoparticle-Liquid Crystalline Elastomer Composites

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including a uniquely high-stroke reversible mechanical actuation triggered by external stimuli. Fundamentally, all such stimuli affect the degree of liquid crystalline order in the polymer chains cross-linked into an elastic network. Heat and the resulting thermal actuation act by promoting entropic disorder, as does the addition of solvents. Photo-isomerization is another mechanism of actuation, reducing the orientational order by diminishing the fraction of active rod-like mesogenic units, mostly studied for azobenzene derivatives incorporated into the LCE composition. Embedding nanoparticles provides a new, promising strategy to add functionality to LCEs and ultimately enhance their performance as sensors and actuators. The motivation for the combination of nanoparticles with LCEs is to provide better-controlled actuation stimuli, such as electric and magnetic fields, and broad-spectrum light, by selecting and configuring the appropriate nanoparticles in the LCE matrix. Here we give an overview of recent advances in this area with a focus on preparation, physical properties and actuation performance of the resultant nanocomposites.