Synthesis and amphiphilic properties of decanoyl esters of tri- and tetraethylene glycol

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.

Graphical abstractTwo pure decanoyl esters of tri- and tetraethylene glycol were synthesized. Their amphiphilic properties are similar to their ether counterparts with reduced liquid crystalline regions due to hindered molecular packing.Figure optionsDownload full-size imageDownload as PowerPoint slide