Synthesis of a liquid crystalline azobenzene monomer for photoalignment of ferroelectric liquid crystals

A liquid crystalline dimethacrylate‐based monomer containing an azobenzene group was synthesized. The miscibility of the azo monomer and its crosslinked polymer network with ferroelectric liquid crystals (FLCs) was improved by the liquid crystallinity of the monomer. By performing thermal polymerization of the azo monomer dissolved in a FLC host under linearly polarized visible light irradiation, following a pre‐irradiation with unpolarized UV light at room temperature, bulk alignment of the FLC could be induced in the absence of surface orientation layers, as a result of the photo‐orientation of azobenzene moieties related to the reversible trans–cis photoisomerization of the chromophore. The optical and rubbing‐free alignment of a FLC could be achieved with as few as 0.5 wt % of the azo polymer network. This represents a step toward the preparation of uniform samples of photoaligned FLC by reducing the amount of the azo polymer network that may be phase‐separated from the FLC host.