M. Hossain, M. Islam, T. Okano
Jun 24, 2002
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Influential Citations
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Journal
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Abstract
Abstract A first-order phase transition has been studied by Brewster angle microscopy in mixed monolayers of 2-hydroxyethyl laurate (2-HEL) and two anionic surfactants, sodium 3,6,9,12-tetraoxa-octacosanoate (TOOCNa) and sodium 3,6,9,12-tetraoxa-triacontanoate (TOTCNa) at the air–water interface. Condensed phase domains are observed on the surface of a mixed solution containing 1.0×10 −5 M each of 2-HEL and of TOOCNa or TOTCNa up to 20 °C. This concentration of 2-HEL is much lower than that required for the phase transition in the pure system at the studied temperatures. The phase transition pressures ( π t ) of all the systems increase with increasing temperature. The π t of 2-HEL-TOOCNa system almost corresponds to that of pure 2-HEL at a definite temperature. In contrast, the π t of 2-HEL-TOTCNa system is lower than the corresponding value of 2-HEL. The shapes and the textures of the domains formed in the mixed system are different to those formed in the pure system. The formed domains in the mixed system have a circular shape with internal segments whereas those of 2-HEL have a fingering pattern with an optical isotropy at the same temperature. A large variety of defects are found in the domains formed in the mixed system. Furthermore, these domains undergo fusion while touching each other.