Improvement of light switching contrast of liquid crystalline composite gel by adding polar organic solvent

The aggregation structure and electro-optical properties were investigated for novel liquid crystalline composites composed of a low molecular weight gelator and a low molecular weight liquid crystal. The gelator spontaneously aggregated through intermolecular hydrogen bonding and formed spherulite-like and fiber-like aggregation structures in the composite. By the addition of a solvent with a high dielectric constant and a large dipole moment, such as dimethyl sulfoxide, the number of the spherulite-like structures in the composite decreased strikingly due to affecting the hydrogen bonding of the self-assembling gelators in the composite, resulting in a higher light transmission state upon an application of an a.c. electric field. Dimethyl sulfoxide was found to be an effective agent for improving the electro-optical properties of (gelator/liquid crystal) composite gel.