Surface activity of some merocyanines and spiropyrans at liquid-liquid interfaces

• Published in: Journal of colloid and interface science 1970-01, Vol.33 (1), p.8-15
• Main Authors: Van Voorhis, J.J, Cartmell, J.V, Hsieh, P.Y
• Format: Article
• Language: English
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/0021-9797(70)90065-2

Interfacial tension lowerings at water-organic liquid interfaces have been measured for some merocyanines and spiropyrans by the pendant drop method. Merocyanine dyes are found to be surface active at the water-organic liquid interface. Colored species of the photochromic spiropyrans are also surface active at the water-organic liquid interface, whereas the colorless forms are not. The surface activity of the colored species of spiropyrans is similar to that of analogous merocyanine dyes. The interfacial tensions of water and organic liquid systems which contain photochromic spiropyrans can be decreased by irradiation with ultraviolet radiation and can subsequently be increased by removal of the ultraviolet radiation. The extent of the interfacial tension lowerings by the spiropyrans is largely dependent upon the degree of solubility and concentration of the dye in the organic liquid.