title: Formation of water-in-CO(2) microemulsions with non-fluorous surfactant Ls-54 and solubilization of biomacromolecules.
abstract: The solubility of Ls-54 surfactant in supercritical CO(2) was determined. It was found that the surfactant was highly soluble in SC CO(2) and the water-in-CO(2) microemulsions could be formed, despite it being a non-fluorous and non-siloxane nonionic surfactant. The main reasons for the high solubility and formation of the microemulsions may be that the surfactant has four CO(2)-philic groups (propylene oxide) and five hydrophilic groups (ethylene oxide) and its molecular weight are relatively low. The results of this work provide useful information for designing CO(2)-soluble non-fluorous and non-siloxane surfactants. The phase behavior of the CO(2)/Ls-54/H(2)O system, solvatochromic probe study, and the UV spectrum of lysozyme proved the existence of water domains in the SC CO(2) microemulsions. The method of synchrotron radiation small-angle X-ray scattering was used to obtain the structural information on the Ls-54 based water-in-CO(2) reverse micelles. By using the Guinier plot (ln I(q) versus q (2)) on the data sets in a defined small q range (0.022-0.040 A(-1)), the radii of the reverse micelles were obtained at different pressures and molar ratio of water to surfactant, W(0), which were in the range of 20.4-25.2 A.
authors.affiliation: Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100 080, China.
authors.forename: Juncheng
authors.initials: J
authors.lastname: Liu
authors.forename: Buxing
authors.initials: B
authors.lastname: Han
authors.forename: Jianling
authors.initials: J
authors.lastname: Zhang
authors.forename: Ganzuo
authors.initials: G
authors.lastname: Li
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Baozhong
authors.initials: B
authors.lastname: Dong
mesh_terms: D001391:Azo Compounds / Q000737:chemistry; D001704:Biopolymers / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D009113:Muramidase / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D001704:Biopolymers; D004655:Emulsions; D013501:Surface-Active Agents; D014867:Water; D002245:Carbon Dioxide; C100258:methyl orange; D009113:Muramidase