1. Department of Physical Chemistry, Division of Materials Science and Chemical Engineering, Yokohama National University, Tokiwadai 156, Hodogaya-ku, Yokohama 240, Japan, Research and Development Department, Procter & Gamble Far East, Inc., 17, Koyo-cho Naka 1-chome, Higashinada-ku, Kobe 658, Japan, and Departamento de Tensioactivos, CID, C.S.I.C., Jordi Girona 18-26, 08034 Barcelona, Spain