Nonionic surface-active agents. Part VI. Phase equilibria in binary and ternary systems containing nonionic surface-active agents

Abstract

Phase equilibrium diagrams have been obtained for the following binary and ternary systems containing nonionic surface-active agents of the monoalkyl polyether type, C m H 2 m+1 (O·CH 2·CH 2) n OH, (C m E n ): C 6E 6 + H 2O + 4-chloro-3,5-xylenol, benzene, n-octanol, or cyclo-hexane; C 6E 2 + H 2O + the same four solutes; C 10E 6 + H 2O; C 10E 6 + H 2O + 4-chloro-3,5-xylenol. The ternary systems were studied at 20°C. The results are compared with previous work on ionic surface-active agents. The major differences between the two types are due to the reduced water solubility of nonionic compounds at elevated temperatures and to their lower melting points. Nonionic ethers have less tendency to form liquid crystal than ionic surface-active agents, although in the C 10E 6 ternary system a liquid crystal phase was found at low concentrations of the glycol (<1%). The complex equilibria found in this system, which includes a region where three isotropic liquid phases are found, has been interpreted partly on the basis of G. S. Hartley's discussion of nonionic surface-active agents (1).