Photo-sensitivity of dye-doped liquid crystal elastomers

Monodomain nematic Liquid Crystal Elastomers (LCEs) are unusual materials, that can undergo uniaxial contraction in response to liquid crystal phase changes. The most straightforward way to bring about such a change is by direct heating, but heat is not an ideal stimulus if the material is to be used in most applications; it is therefore advantageous to sensitize the material to an alternative stimulus, such as light. LCEs containing different dye concentrations have been synthesized, and it is shown that the presence of the dye does sensitize the material to light; crucially, the dye does not have to contain the photo-isomerizable azobenzene functional group (used in many other studies on photosensitive LCEs) in order for this to be the case. This finding is of value since it indicates that any strongly light-absorbing dye, when subjected to light irradiation, is capable of thermally triggering a phase change.