PHASE-BEHAVIOR OF METHOXYPOLYOXYETHYLENE DODECANOATE AS COMPARED TO POLYOXYETHYLENE DODECYL ETHER AND POLYOXYETHYLENE METHYL DODECYL ETHER

The phase behavior of binary systems composed of water and nonionic surfactants were investigated. The nonionic surfactants studied were the methoxypolyoxyethylene dodecanoates (R11COO(EO)nCH3, n = 4.9, 6.1, 7.3, 9.3, and 12.8, where n is the average number of oxyethylene units). The phase behaviors of R11COO(EO)nCH3 were compared with those of the polyoxyethylene dodecyl ethers (R12O(EO)pH) and polyoxyethylene methyl dodecyl ethers (R12O(EO)qCH3) which have been previously reported. It was found that the R11COO(EO)nCH3s have lower cloud points and lower upper limit temperatures for the existence of the mesophase as compared to the other two types. A R11COO(EO)12.8CH3/water system had favorable solution properties for practical use, such as a relatively narrow hexagonal liquid crystalline region and a lower melting point than the ordinary alcohol ethoxylate type nonionics.