A calamitic mesogenic near-infrared absorbing croconaine dye/liquid crystalline elastomer composite.

In this work, we report the first example of a calamitic mesogenic near-infrared (NIR) absorbing organic dye, made by functionalizing a thiophene-croconaine chromophore rigid core with two symmetric long flexible alkyl chains. The liquid crystal (LC) NIR dye exhibits a sharp and intense NIR absorption band with a maximum absorption peak at 796 nm. Taking advantage of the improved solubility of dispersed in mesogenic molecules, a homogeneously-aligned mono-domain liquid crystalline elastomer (LCE)/ composite film is successfully prepared by applying the classical LC-cell-alignment method and photo-polymerization of photocurable LC monomer mixtures. This LCE/ composite film performs a fully reversible contraction/expansion response towards NIR light stimulus due to the photo-thermal heating effect induced by the dye well-dispersed in the LCE matrix.