Method for preparing a liquid crystal-based switching element

A method for the preparation of a window element which is operable in and electrically switchable between an optically clear state and a scattering state, the method comprising the steps of:

• (i) providing a liquid-crystalline medium which comprises one or more mesogenic compounds, one or more chiral compounds and one or more polymerisable mesogenic compounds as a layer interposed between two opposing transparent substrates which are each provided with an electrode,
• wherein the liquid-crystalline medium has a clearing point of 70° C. or more, and
• wherein the one or more polymerisable mesogenic compounds are contained in the medium in an amount, based on the overall contents of the medium, of 4% by weight or less;
• (ii) polymerising the one or more polymerisable mesogenic compounds via photopolymerisation the presence of a direct current electric field in the layer, wherein the direct current electric field has a DC voltage in a range from 30 V to 150 V for a time period of 1 minute to 240 minutes, further comprising polymerising the one or more polymerisable mesogenic compounds in the presence of a direct current electric field in the layer, the applied direct current electric field inducing a homeotropic alignment in the layer comprising the liquid-crystalline medium;
• and
• after performing step (ii), (iii) performing a thermal treatment of the liquid-crystalline medium in the presence of the direct current electric field.