Mechano-Optical Response of Novel Polymer Composites Based on Elastic Polyurethane Matrix Filled with Low-Molar-Mass Cholesteric Droplets

Among the various types of liquid crystalline (LC) structures, the cholesteric mesophase attracts special attention in view of helical supramolecular structure determining their specific optical properties. The helix pitch of cholesteric liquid crystals is very sensitive to mechanical stress, resulting in change of their optical properties and position of selective light reflection peak. Here, films of polymer-dispersed cholesteric liquid crystals based on polyurethane elastomer are prepared and studied. Liquid crystal mixtures based on chiral cholesterol derivatives are uniformly dispersed in the form of micrometer-sized droplets in an elastomeric matrix. A significant mechano-optical response of the composites under the action of deformation is demonstrated, and the change in the position of the selective light reflection band during mechanical stress is studied in detail. A shift in the selective light reflection peak by 100 nm or more is found. This process is accompanied by color transformations of brightly colored films. Such materials can be promising for creating stress and deformation sensors, ripple and bending sensors, and other technical devices.

Automated summary

Polymer-dispersed cholesteric liquid crystal films based on polyurethane elastomer show significant mechano-optical response and changes in the position of the selective light reflection band under deformation. A shift in the selective light reflection peak by 100 nm or more is found, accompanied by color transformations of brightly colored films. These materials hold promise for creating stress and deformation sensors, ripple and bending sensors, and other technical devices.