Well-defined decanoyl triethylene glycol ester and decanoyl tetraethylene glycol ester were synthesized and compared to their ether counterparts (C10E4 and C10E3). Their physicochemical properties i.e. critical micelle concentrations (CMC), cloud points, and equilibrium surface tensions were determined. Binary water-surfactant phase behavior was also studied by polarized optical microscopy. The stability of the ester bond was determined by investigating alkaline hydrolysis of the compounds. It was found that CMC, cloud point and equilibrium surface tension are roughly the same for corresponding ethers and esters. In the binary diagram, the esters form only lamellar phases, the area of which is smaller than that of the ether counterparts. These different behaviors can be related to the modification of the molecular conformation induced by the replacement of the ether group by the ester group. (c) 2007 Elsevier Inc. All rights reserved.