Patent ID: 8956548
Filing Date: 2015-02-17
Classification: C09K,G02F

Abstract:
1. A thermotropic liquid crystal smectic A composition exhibiting a smectic type A phase made up of multiple layers and capable of forming a liquid crystal optical device when sandwiched between a pair of electrodes, wherein: under the influence of different electric fields applied between the electrodes, the alignment of the layers of the composition can become more ordered or more disordered, and the composition has stable states in which the alignment of the layers of the composition are differently ordered including an ordered state, a disordered state, and intermediate states, the composition being such that, once switched to a given state by an electric field, it remains substantially in that state when the field is removed, which composition comprises, in weight %: (a) 25-75% in total of at least one siloxane of the general formula I: wherein (b) 0.001-1% in total of at least one quaternary ammonium ionisable species of the general formula II: wherein: (c) 20-65% in total of at least one polarisable linear molecule having an alkyl chain, the molecule having the general formula III: (d) 2-20% in total of at least one side chain liquid crystal polysiloxane of the general formula IV: and wherein the amounts and nature of the components are selected such that the composition possesses smectic A layering and siloxane-rich sub-layering, as detected by X-ray diffraction.