Photo-driven giant reduction of the Frank elastic constants in a bent-core nematic liquid crystal

摘要

We report the influence of photoisomerization on the splay (K_(11)) and bend (K_(33)) elastic constants in a bent-core nematic doped with a small amount of a calamitic photoactive compound. Trans-cis isomerization of the latter compound results in a large decrease (factor of ～3 for K_(33)) of both the moduli, and K_(33) becoming almost independent of temperature except near the isotropic phase. The observed variations are much larger than can be explained by order parameter changes, and are explained using an argument based on the molecular arrangement.