Synthesis of triphilic, Y-shaped molecular surfactants

Novel multiphilic molecules comprising three chains with antagonistic affinities have been synthesized. These ‘triphilic’ surfactants (FnHmEOy) contain a perfluorinated arm (Fn=CnF2n+1), a hydrocarbon arm (Hm=CmH2m+1), and a methyl-caped, poly(ethylene glycol) arm (EOy=CH3(OC2H4)yO). These moieties have variable lengths (n=5 or 7, m=8, 10, or 14, and y=2–7) and are interconnected in a Y shape; hence, each unit is directly connected to the other two. The key intermediates in the synthetic route are 3-F-alkyl-3-alkyloxypropanoic acids, on which the polar EOy chain is subsequently grafted. Monodisperse methyl-caped diethylene glycol (EO2) and triethylene glycol (EO3) led to the corresponding monodisperse triaffine surfactants. In parallel, a library of five F5H10EOy triaffines (y=3–7) has been obtained simultaneously when starting from the polydisperse methyl-caped poly(ethylene glycol) MPEG 350. Separation of pure individual compounds was achieved through column chromatography on silica gel. The relative concentration of the Z and E isomers has been quantified in the reaction mixtures of the intermediates and final products by 1H NMR (Z largely predominant). Several products have been obtained in their isomerically pure form. Chemical characterization (1H, 13C, and 19F NMR, elemental analysis) was consistent with the expected structures.