Branched alkyldimethylamine oxide surfactants: An effective strategy for the design of high concentration/low viscosity surfactant formulations

Antonio Fabozzi; Irene Russo Krauss; Rosa Vitiello; Marco Fornasier; Luca Sicignano; Stephen King; Stefano Guido; Christopher Jones; Luigi Paduano; Sergio Murgia; Gerardino D'Errico

doi:10.1016/j.jcis.2019.05.052

Branched alkyldimethylamine oxide surfactants: An effective strategy for the design of high concentration/low viscosity surfactant formulations

J Colloid Interface Sci. 2019 Sep 15:552:448-463. doi: 10.1016/j.jcis.2019.05.052. Epub 2019 May 18.

Authors

Affiliations

¹ Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant'Angelo, I-80126 Naples, Italy.
² Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant'Angelo, I-80126 Naples, Italy; CSGI, Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Florence, Italy.
³ Department of Chemical and Geological Sciences, University of Cagliari, s.s. 554 bivio Sestu, Monserrato, CA I-09042, Italy.
⁴ Department of Chemical, Materials and Production Engineering, University of Naples Federico II, P.le V. Tecchio 80, I-80125 Naples, Italy.
⁵ ISIS Pulsed Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom.
⁶ Procter & Gamble Innovation Centre, Strombeek-Bever Temseelan 100, B-1853, Brussels, Belgium.
⁷ CSGI, Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Florence, Italy; Department of Chemical and Geological Sciences, University of Cagliari, s.s. 554 bivio Sestu, Monserrato, CA I-09042, Italy. Electronic address: murgias@unica.it.
⁸ Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant'Angelo, I-80126 Naples, Italy; CSGI, Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Florence, Italy. Electronic address: gerardino.derrico@unina.it.

PMID: 31151022
DOI: 10.1016/j.jcis.2019.05.052

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.

Keywords: Branched tail; Concentrated formulation; Humidity-scan quartz crystal microbalance with dissipation (QCM-D); Phase diagram; Rheology; Zwitterionic surfactants.