CHARACTERISTIC SOLUTION PROPERTIES OF MONOGLYCERYL, DIGLYCERYL, AND TRIGLYCERYL ALKYL ETHERS - LIPOPHOBICITY OF HYDROPHILIC GROUPS

The lipophobicity, i.e., the reciprocal of the saturation concentration of singly dispersed solute, x, in saturated hydrocarbon in equilibrium with water phase, is an important property of amphiphiles. The lipophobicity of oligo(oxyethylene) nonionic surfactants increased about 2 times per oxyethylene group, and that of a secondary hydroxyl group, CH(OH), corresponded to about 4.6 oxyethylene groups (on weight basis 6.7 times higher lipophobicity). Due to the change from CH20 (ether) to COO (ester), the lipophobicity increased about 5 times. Although the lipophobicities of hexa(oxyethylene) dodecyl ether and monoglyceryl a-dodecyl ether are close to each other, the former is water-soluble whereas the latter is oil-soluble at 25. The fact that the surfactants used in oil media are polyol type (e.g., Span) and not oxyethylene type coincides with the strong lipophobicity of OH groups and their oil-soluble tendency, revealed in the present study. It is evident that monoglyceryl alkyl ether or ester is an excellent oleophilic cosurfactant. The effect of temperature on the solution properties of glyceryl alkyl compounds was much smaller than that of oligo(oxyethylene) alkyl ethers. Thus, polyol-type nonionic amphiphiles seem promising in practical applications due to their high lipophobicity and temperature insensitivity. © 1990 American Chemical Society. all right reserved. © 1990, American Chemical Society. All rights reserved.