Hypothesis: The rational design of branched-tail surfactants is a suitable strategy to obtain low-viscosity surfactant-rich isotropic aqueous mixtures with negligible effects on biodegradability. This opens a way to the design of concentrated ("water-free") surfactant formulations, highly attractive for their ecological and economic benefits. Experiments: The aggregation behaviour of N,N-dimethyl-2-propylheptan-1-amine oxide (C10DAO-branched) in aqueous mixtures is investigated across the entire composition range by polarized optical microscopy, small angle X-ray and neutron scattering, electron paramagnetic resonance, and pulse-gradient stimulated echo nuclear magnetic resonance. The humidity scanning quartz crystal microbalance with dissipation monitoring technique is validated as a tool for the fast screening of surfactants phase behaviour. Furthermore, the shear viscosities and viscoelastic moduli of the systems are determined by rheological measurements. Findings: With respect to the linear isomer, C10DAO-branched presents a much lower tendency to form lyotropic liquid crystalline phases. Except for a narrow composition and temperature range in which a lamellar structure is observed, C10DAO-branched aqueous mixtures are isotropic liquids whose microstructure changes, with increasing concentration, from micellar solutions to unstructured dispersions of hydrated surfactant molecules. Low-viscosity was found for all these mixtures, including the most concentrated ones. Thus, the introduction of a single short side-chain in the tail is demonstrated to be an effective approach to increase the active concentration in surfactant formulations.
Branched alkyldimethylamine oxide surfactants: An effective strategy for the design of high concentration/low viscosity surfactant formulations / Fabozzi, Antonio; Russo Krauss, Irene; Vitiello, Rosa; Fornasier, Marco; Sicignano, Luca; King, Stephen; Guido, Stefano; Jones, Christopher; Paduano, Luigi; Murgia, Sergio; D'Errico, Gerardino. - In: JOURNAL OF COLLOID AND INTERFACE SCIENCE. - ISSN 0021-9797. - 552:(2019), pp. 448-463. [10.1016/j.jcis.2019.05.052]
Branched alkyldimethylamine oxide surfactants: An effective strategy for the design of high concentration/low viscosity surfactant formulations
Fabozzi, Antonio;Russo Krauss, Irene;Vitiello, Rosa;Sicignano, Luca;Guido, Stefano;Paduano, Luigi;D'Errico, Gerardino
2019
Abstract
Hypothesis: The rational design of branched-tail surfactants is a suitable strategy to obtain low-viscosity surfactant-rich isotropic aqueous mixtures with negligible effects on biodegradability. This opens a way to the design of concentrated ("water-free") surfactant formulations, highly attractive for their ecological and economic benefits. Experiments: The aggregation behaviour of N,N-dimethyl-2-propylheptan-1-amine oxide (C10DAO-branched) in aqueous mixtures is investigated across the entire composition range by polarized optical microscopy, small angle X-ray and neutron scattering, electron paramagnetic resonance, and pulse-gradient stimulated echo nuclear magnetic resonance. The humidity scanning quartz crystal microbalance with dissipation monitoring technique is validated as a tool for the fast screening of surfactants phase behaviour. Furthermore, the shear viscosities and viscoelastic moduli of the systems are determined by rheological measurements. Findings: With respect to the linear isomer, C10DAO-branched presents a much lower tendency to form lyotropic liquid crystalline phases. Except for a narrow composition and temperature range in which a lamellar structure is observed, C10DAO-branched aqueous mixtures are isotropic liquids whose microstructure changes, with increasing concentration, from micellar solutions to unstructured dispersions of hydrated surfactant molecules. Low-viscosity was found for all these mixtures, including the most concentrated ones. Thus, the introduction of a single short side-chain in the tail is demonstrated to be an effective approach to increase the active concentration in surfactant formulations.File | Dimensione | Formato | |
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