Preparation and evaluation of monodisperse nonionic surfactants based on fluorine-containing dicarbamates

Novel bipodal surfactants of fluorine-containing carbamate type were synthe sized with satisfactory yields from the action of fluorinated diisocyanates on oligooxyethylmonomethylated ethers without solvent. The synthetic pathw ays via malonic intermediates were elaborated in order to use low-price com mercially available compounds such as 2-F-alkylethyl iodides and oligooxyet hylmonomethylated ethers as starting materials. This new class of nonionic surfactants contains one hydrophobic part and one oleophobic part, and show s peculiar properties due to the presence of two hydrophilic parts (bipodal ). All these compounds are monodisperse, i.e, include a perfectly defined n umber of oxyethylene units. Compared with their bipodal homologues previous ly described within the F-alkylated series, these new structures were easil y obtained from commercial raw materials and are stable against pH media. T he evaluation of their behavior at the air-water interface has been studied by measurements of surface tension versus concentration. This allows us to show clearly the variation of the critical micelle concentration (cmc) fro m 1.1 x 10(-5) to 9.8 x 10(-3) mol.l(-1), and of the surface area per surfa ctant molecule versus studied structures. The dicarbamates of oligooxyethyl monomethylether of 3-(F-alkyl)propyl so realized exhibit noteworthy propert ies as nonionic fluorinated surfactants. (C) 2000 Academic Press.