Abstract
| Original language | English |
|---|---|
| Journal | Langmuir |
| DOIs | |
| Publication status | Published - 11 Feb 2019 |
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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 journal › Article
TY - JOUR
T1 - Water-in-CO2 microemulsions stabilized by fluorinated cation-anion surfactant pairs
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
PY - 2019/2/11
Y1 - 2019/2/11
N2 - 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.
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.
U2 - 10.1021/acs.langmuir.8b03942
DO - 10.1021/acs.langmuir.8b03942
M3 - Article
JO - Langmuir
JF - Langmuir
SN - 0743-7463
ER -