Flexible ferroelectric liquid crystal devices for roll-up displays

We have been developing a novel-structure ferroelectric liquid crystal (FLC) device containing micropolymers for roll-up screen displays. We studied bending-iteration tolerance of a flexible FLC device containing polymer-fiber networks and lattice-shaped walls. Although conventional bistable FLC devices have the disadvantage of fragile smectic layer structures, the polymer walls fasten two flexible thin plastic substrates and keep the FLC layer thickness constant even when the device is bent. Otherwise, the anchoring of the molecular-aligned polymer networks enables FLC to obtain monostable molecular switching. We first examined mechanical stability of smectic layers in monostable FLC devices by shearing two substrates. It was found that the monostable FLC device shows good tolerance without generating alignment defects, in comparison with the bistable FLC device. We then formed a flexible device of a size of 100mm x 100mm by utilizing two-step photopolymerization-induced phase separation of an FLC/monomer solution film coated by a flexographic printing method. As a result, the 2-mum-thick cured composite film supported the two 100-mum-thick plastic substrates. We repeatedly bended it at a minimum curvature radius of 20mm in period time of 20s. As a result, its microscopic texture and electrooptic effect were not changed even after bending of 1000 times. The spatial uniformity of the flexible device was kept for more than 10000-times bending.