Two fatty acids, perfluorononanoic acid (C8F17COOH) and nonanoic acid (C8H17COOH), were mixed with a cationic hydrocarbon surfactant, tetradecyltrimethylammonium hydroxide (TTAOH), in aqueous solutions for comparative investigation. Phase behaviors of the two systems are quite different because of the special properties of the fluorocarbon chains. For the C8H17COOH/TTAOH/H2O system, a single Lα phase region with phase transition ...