Water-in-CO2 microemulsions stabilized by fluorinated cation-anion surfactant pairs

Masanobu Sagisaka, Tatsuya Saito, Atsush Yoshizawa, Sarah E. Rogers, Frederic Guittard, Christopher Hill, Julian Eastoe, Marijana Blesic

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

High water-content water-in-supercritical CO2 (W/CO2) microemulsions are considered to be green, universal solvents, having both polar and nonpolar domains. Unfortunately, these systems generally require environmentally-unacceptable stabilizers like long and/or multi fluorocarbon-tail surfactants. Here, a series of catanionic surfactants having environmentally-friendly fluorinated C4-C6-tails have been studied in terms of interfacial properties, aggregation behavior and solubilizing power in water and/or CO2. The lowest surface tension and the critical micelle concentration of these catanionic surfactants are respectively lower by ~9 mN/m and 100 times than the constituent single FC-tail surfactants. Disk-like micelles in water were observed above the respective critical micelle concentrations, implying the catanionic surfactants to have a high critical packing parameter (CPP), which should also be suitable to form reverse micelles. Based on visual observation of phase behavior, FT-IR spectroscopic and small-angle neutron scattering (SANS) studies, one of the three catanionic surfactants tested was found to form transparent single-phase W/CO2 microemulsions with a water-to-surfactant molar ratio up to ~50. This is the first successful demonstration of the formation of W/CO2 microemulsion by synergistic ion-pairing of anionic and cationic single-tail surfactants. It indicates that catanionic surfactants offer a promising approach to generate high water-content W/CO2 microemulsions.
Original languageEnglish
JournalLangmuir
DOIs
Publication statusPublished - 11 Feb 2019

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Microemulsions
Surface-Active Agents
Anions
Cations
Surface active agents
Negative ions
Positive ions
surfactants
anions
cations
Water
water
micelles
Critical micelle concentration
Micelles
Water content
moisture content
Stabilizers (agents)
Fluorocarbons
visual observation

Cite this

Sagisaka, Masanobu ; Saito, Tatsuya ; Yoshizawa, Atsush ; Rogers, Sarah E. ; Guittard, Frederic ; Hill, Christopher ; Eastoe, Julian ; Blesic, Marijana. / Water-in-CO2 microemulsions stabilized by fluorinated cation-anion surfactant pairs. In: Langmuir. 2019.
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abstract = "High water-content water-in-supercritical CO2 (W/CO2) microemulsions are considered to be green, universal solvents, having both polar and nonpolar domains. Unfortunately, these systems generally require environmentally-unacceptable stabilizers like long and/or multi fluorocarbon-tail surfactants. Here, a series of catanionic surfactants having environmentally-friendly fluorinated C4-C6-tails have been studied in terms of interfacial properties, aggregation behavior and solubilizing power in water and/or CO2. The lowest surface tension and the critical micelle concentration of these catanionic surfactants are respectively lower by ~9 mN/m and 100 times than the constituent single FC-tail surfactants. Disk-like micelles in water were observed above the respective critical micelle concentrations, implying the catanionic surfactants to have a high critical packing parameter (CPP), which should also be suitable to form reverse micelles. Based on visual observation of phase behavior, FT-IR spectroscopic and small-angle neutron scattering (SANS) studies, one of the three catanionic surfactants tested was found to form transparent single-phase W/CO2 microemulsions with a water-to-surfactant molar ratio up to ~50. This is the first successful demonstration of the formation of W/CO2 microemulsion by synergistic ion-pairing of anionic and cationic single-tail surfactants. It indicates that catanionic surfactants offer a promising approach to generate high water-content W/CO2 microemulsions.",
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Water-in-CO2 microemulsions stabilized by fluorinated cation-anion surfactant pairs. / Sagisaka, Masanobu ; Saito, Tatsuya; Yoshizawa, Atsush; Rogers, Sarah E.; Guittard, Frederic; Hill, Christopher; Eastoe, Julian; Blesic, Marijana.

In: Langmuir, 11.02.2019.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Sagisaka, Masanobu

AU - Saito, Tatsuya

AU - Yoshizawa, Atsush

AU - Rogers, Sarah E.

AU - Guittard, Frederic

AU - Hill, Christopher

AU - Eastoe, Julian

AU - Blesic, Marijana

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AB - High water-content water-in-supercritical CO2 (W/CO2) microemulsions are considered to be green, universal solvents, having both polar and nonpolar domains. Unfortunately, these systems generally require environmentally-unacceptable stabilizers like long and/or multi fluorocarbon-tail surfactants. Here, a series of catanionic surfactants having environmentally-friendly fluorinated C4-C6-tails have been studied in terms of interfacial properties, aggregation behavior and solubilizing power in water and/or CO2. The lowest surface tension and the critical micelle concentration of these catanionic surfactants are respectively lower by ~9 mN/m and 100 times than the constituent single FC-tail surfactants. Disk-like micelles in water were observed above the respective critical micelle concentrations, implying the catanionic surfactants to have a high critical packing parameter (CPP), which should also be suitable to form reverse micelles. Based on visual observation of phase behavior, FT-IR spectroscopic and small-angle neutron scattering (SANS) studies, one of the three catanionic surfactants tested was found to form transparent single-phase W/CO2 microemulsions with a water-to-surfactant molar ratio up to ~50. This is the first successful demonstration of the formation of W/CO2 microemulsion by synergistic ion-pairing of anionic and cationic single-tail surfactants. It indicates that catanionic surfactants offer a promising approach to generate high water-content W/CO2 microemulsions.

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