Thermo-reversible liquid-crystal gels:: Towards a new processing route for twisted nematic displays

Thermo-reversible gels of the liquid-crystal system LC-TL213 with 12-hydroxyoctadecanoic acid (HOA) were cast in a twisted nematic (TN) configuration that is switchable by AC electric fields. Critical in this process was to choose a processing temperature higher than the sol-gel temperature but lower than the nematic-isotropic transition of the system. The latter condition originates in the phase diagram of the system which displays a monotectic-type point at which a liquid is in equilibrium with a solid and a mesophase. The solid-like nature of the gels produced, combined with their electro-optical activity, opens the possibility to manufacture flexible TN cells via continuous processes as an alternative to the currently employed batch-type methods.