title: Structure and rheology of gel nanostructures from a vitamin C-based surfactant.
abstract: The structure and rheology behaviour of gels produced by water dispersions of a vitamin C-derived surfactant (ascorbyl-6-O-dodecanoate) were investigated by means of SAXS and rheology experiments for the first time. The gel state is formed upon heating and is due to an anisotropic expansion of the tightly compact lamellar structure. The phase transition involves primarily the melting of the alkyl chains and a significant increment in the interlamellar water layer. In particular, our results show that in the gel the hydrophobic chains are in a liquid-like state, as in the core of a micelle, while the head groups release their acidic proton, become negatively charged and determine the onset of strong electrostatic interactions between facing lamellae. The full hydration of the anionic head groups and the uptake of a significant amount of water increase the interlamellar thickness and stabilise the gel structure. Rheology and SAXS measurements together provide an updated picture for the gel state. Moreover, for the first time we show the presence of a concentration threshold, above which the self-assembled aggregates interact more strongly and deplete some of the water that is retained in the interlamellar region.
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Carretti
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it and Department of Applied Mathematics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Virginia
authors.initials: V
authors.lastname: Mazzini
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Fratini
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it.
authors.forename: Moira
authors.initials: M
authors.lastname: Ambrosi
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it and Enzo Ferroni Foundation, 50019 Sesto Fiorentino, Firenze, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Dei
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it and Enzo Ferroni Foundation, 50019 Sesto Fiorentino, Firenze, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Baglioni
authors.affiliation: Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. PLN@csgi.unifi.it and Enzo Ferroni Foundation, 50019 Sesto Fiorentino, Firenze, Italy.
authors.forename: Pierandrea
authors.initials: P
authors.lastname: Lo Nostro