Abstract
Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions. Despite the technological and fundamental importance of these long-range changes, there is no good physical property with which to express them for the liquid crystal. Here, we show direct measurements of the propagation of structural or orientational changes due to long-range molecular interactions in liquid crystals. We induced a patterned phase transition in a liquid crystal via illumination with a fringe pattern and observed the propagation of the phase-transition region. We determined that the propagation occurred in a ballistic manner with a velocity of 80–110 m/s and that two types of propagation—side-by-side and head-to-tail molecular interactions—were found.
Highlights
Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions
Other examples are found in liquid crystals (LCs), which can be encountered in nature in biological membranes, silks and the like
An active capsule composed of LCs was demonstrated, and the motion was controlled by a small number of defects, which means the position at which the direction of molecular orientation could not be defined[4]
Summary
Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions. A patterned light was illuminated onto an LC cell, in which guest dye molecules were put inside an LC for light absorption, causing the phase transition of the LC in a controlled way, and the propagation of the phase-transition region was measured by an optical technique known as transient grating (TG).
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