Formation of polyhedral vesicle gels from catanionic mixtures of hydrogenated and perfluorinated surfactants: effect of fluoro-carbon alkyl chain lengths. Issue 40 (4th October 2018)

• Record Type: Journal Article
• Authors: Zhang, Juan; Pi, Benxiang; Wang, Xiaomeng; Yang, Zihao; Lv, Qichao; Lin, Meiqin
• Is Part Of: Soft matter. Volume 14:Issue 40(2018)
• Page Start: 8231
• Page End: 8238
• Publication Date: 2018-10-04
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c8sm01787e
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Phase transition from spherical vesicles to faceted vesicles and gels. Abstract : The effects of alkyl chain length of anionic fluorinated fatty acid surfactants, C n F2 n +1 COOH ( n = 7–11), mixed with one cationic hydrocarbon surfactant, tetradecyltrimethylammonium hydroxide (TTAOH), on the formation of polyhedral vesicle gels were investigated in aqueous solutions. On the basis of phase behavior mapping, C8 F17 COOH, C9 F19 COOH, C10 F21 COOH and C11 F23 COOH except C7 F15 COOH all formed polyhedral vesicle gels when they were mixed with TTAOH under certain mixed ratios, which was demonstrated by freeze-fracture transmission electron microscopy (FF-TEM) measurements. Meanwhile, the following observation was not observed: the longer the fluorinated alkyl chain, the more effective the formation of gels by fluorinated fatty acids. The formation of the faceted vesicle gels was determined both by the rigidity of the fluorinated alkyl chain and the co-crystallization of fluorocarbon chains and hydrocarbon chains, as revealed by the results of differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and 19 F NMR measurements. Furthermore, the polyhedral vesicle gels showed high viscoelasticity, which increased clearly with increasing fluorinated alkyl chain length, indicating that the viscoelastic property of the polyhedral vesicle gel was a result of the crystalline state of the polyhedral vesicle bilayers at room temperature. As far as we know, such polyhedral vesicle gels formed from perfluorinated and hydrocarbon surfactant mixtures have been rarely reported. Our study can be a great advancement in fundamental research of surfactant vesicle gels.