Effect of Fluorocarbon and Hydrocarbon Chain Lengths in Hybrid Surfactants for Supercritical CO₂

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms The W0 value of 80 is the highest for a HC-FC hybrid surfactant, matching the highest value reported for a FC surfactant which contained more FC groups. High-pressure SANS measurements from FCmHCn/D2O/CO2 microemulsions were consistent with growth of the microemulsion droplets with increasing W0. In addition, not only spherical reversed micelles but also non-spherical assemblies (rodlike or ellipsoidal) were found for the systems with FC6-HCn (n = 4-6). At fixed surfactant concentration and W0 (17mM and W0 = 20). The longest reversed micelles were obtained for FC6-HC6 where a mean aspect ratio of 6.3 was calculated for the aqueous cores.

A class of efficient short-chain fluorinated catanionic surfactants

“…Fluorosurfactants are used as additives for paints, coatings, and fire extinguisher foams, wetting agents, cleaners for hard surfaces, plane hydraulic fluids, emulsifying and dispersing agents, surface protectors, etc. [14][15][16][17][18][19][20][21] The most investigated fluorinated surfactants are anionic [21][22][23] and non-ionic. 12,13 The presence of both hydrophilic heads and fluorinated chain(s) in their structures makes some fluorosurfactants also efficient in stabilisation of water-in-CO 2 microemulsions.…”

New Class of Amphiphiles Designed for Use in Water-in-Supercritical CO2 Microemulsions

“…For example, DeSimone et al 17 reported that dendrimers with a fluorinated shell were soluble in liquid CO2, and could extract an ionic dye methyl orange in the dendrimer core from water phase. Liu et al 18 19 The optimal HC-tail and FC-tail length in this hybrid surfactant was found to be n = 4 and m = 6 respectively (i.e. FC6-HC4).…”

“…The family of compounds Nohead FC6-HCn (n = 2, 4, 6) and Nohead HC6-HC4 are the intermediates obtained before the sulfonation step used to obtain the hybrid surfactants sodium 1-oxo-1- as shown in Figure 1. All of these compounds were synthesized and purified as described in the earlier paper 19…”

“…A detailed description of the experimental apparatus and procedures for the measurements can be found elsewhere. 11,12,19 In order to examine the formation of aqueous cores in W/CO2 µEs, UV-visible absorption spectroscopy measurements were performed on a double-beam spectrophotometer (Hitachi High-Technologies, Co., U-2810) with a quartz window pressure cell (volume: 1.5 cm 3 ) that was connected to the experimental apparatus. Methyl orange (MO) was used as a trace marker dye.…”

“…The data were normalized for transmission, empty cell, solvent background, and pressure induced changes in cell volume as before. 19,20 Pre-determined amounts of D2O and hybrid compound, where the molar concentration of hybrid compound in CO2 was fixed at 50 or 80 mM at the measurement conditions, were loaded into the Thar cell. Then, CO2 (11.3g), was introduced into the cell by using a high pressure pump, and the compound/D2O/CO2 mixture was pressurized up to the experimental pressures at 45 ºC by decreasing the inner volume of the Thar cell.…”