THE CATANIONIC SYSTEM DODECYLTRIMETHYLAMMONIUM HYDROXIDE-N-DODECANEPHOSPHONIC ACID-WATER - TRIANGULAR PHASE-DIAGRAM

The triangular phase diagram of the system dodecyltrimethylammonium hy droxide (DTAOH)-dodecanephosphonic acid (H2DP)-water was studied by se veral techniques. The DTAOH-rich zone could not be studied because DTA OH decomposed when it was dried. Pure H2DP only forms lamellar mesopha ses with water. The inclusion of DTAOH in the system produces the appe arance of cubic and hexagonal mesophases. The gradual increase in DTAO H proportion lead to the gradual reduction in the existence of the lam ellar mesophase domain, and increase of the hexagonal liquid crystal d omain. At high DTAOH content, the lamellar mesophase disappeared. This behavior was explained by the gradual destruction of the hydrogen-bon ded structure in the polar headgroup layer of liquid crystal aggregate s. H2DP-rich anhydrous crystals were triclinic.