THE AGGREGATION OF N-DODECANEPHOSPHONIC ACID IN WATER

Several techniques were employed to study the aggregation of n-Dodecan ephosphonic Acid (DPA) in water. At 22 degrees C, the solubillity of D PA increases, probably due to the formation of small premicellar aggre gates. The CMC is (5.4 +/- 2.4) x 10(-4) mol . dm(-3) and the solubili ty reaches the CMC value at 26 degrees C. At 30 degrees C and at a con centration of about 9 x 10(-3) mol . dm(-3), a lamellar mesophase appe ars. Both micelles and liquid crystal lamellae are almost uncharged. T heir polar heads have strong hydrogen bonds between them. The ionizati on of DPA molecules in micelles and mesophase structures is strongly r educed in comparison with monomerically dissolved molecules.