Symmetric and Asymmetric Bolaamphiphiles from Ascorbic Acid
journal contributionposted on 2011-10-13, 00:00 authored by Christian Dolle, Pietro Magrone, Sergio Riva, Moira Ambrosi, Emiliano Fratini, Niccolò Peruzzi, Pierandrea Lo Nostro
The properties of novel bolaamphiphiles that carry epimers of vitamin C (l-ascorbic acid and/or d-isoascorbic acid) as hydrophilic head groups, and an interconnecting aliphatic C12 chain (DD, DL, and LL) were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) in the solid state (anhydrous powders) and in aqueous dispersions as a function of the surfactant concentration. Upon heating, the aqueous dispersions undergo a phase transition from a hydrated semicrystalline “coagel” to a micellar phase. The results suggest that the headgroup chirality determines the formation of either inter- or intramolecular hydrogen bonds between the polar heads, which affect the phase behavior and structural properties of the nanoassemblies produced by these surfactants in water dispersions. The DSC data of aqueous dispersions were analyzed to obtain the size distribution of the pores in the coagel state.
vitamin CDSC dataintramolecular hydrogen bondsAsymmetric Bolaamphiphilesacidsize distributionSAXSXRDwater dispersionscoagel stateFTIRscanning calorimetryphase transitioninterconnecting aliphatic C 12 chainAscorbic AcidThe propertiesDLDDmicellar phaseheadgroup chiralitysurfactant concentrationLLhead groupsTGAnovel bolaamphiphilesphase behavior