The interfacial and micellization properties of binary and ternary mixtures of Gemini homologues, viz., tetramethylene-1,4-bis(N-hexadecyl-N,N-dimethylammonium bromide), pentamethylene-1,5-bis(N-hexadecyl-N,N-dimethylammonium bromide), and hexamethylene-1,6-bis(N-hexadecyl-N,N-dimethylammonium bromide), with various compositions were investigated at 25 degrees C using conductometric and tensiometric measurements. The micellar and adsorption characteristics like composition, activity coefficients, mutual interaction parameter, minimum area per molecule, free energy of micellization and adsorption have been evaluated and compared. The ideality/nonideality of the mixed micelles were tested in light of Clint, Rubingh, and Rubingh-Holland approaches. The mixed systems were found to undergo synergistic interaction, more so in mixed monolayer than in mixed micelle formation, and the micellar and interfacial properties were found to depend on the selection of surfactant pairing.
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http://dx.doi.org/10.1016/j.jcis.2009.12.037 | DOI Listing |
Soft Matter
October 2021
Department of Chemistry, University of Colorado, Boulder, CO 80309, USA.
Langmuir
March 2020
Department of Chemistry, University of Minnesota, 207 Pleasant St. S. E., Minneapolis, Minnesota 55455, United States.
We report detailed small-angle X-ray scattering (SAXS) studies of the impact of variable -decane loadings on the lyotropic liquid crystalline (LLC) phase behaviors of homologous bis(tetramethylammonium) gemini didecanoate surfactants , which derive from dimerizing decanoic acid through its α-carbon with hydrocarbyl linkers -(CH)- where = 3, 4, 5, and 6. amphiphiles with = 3 or 5 exhibit a strong propensity to form normal double gyroid (G) LLC network mesophases over wide surfactant hydration ranges, as compared to homologues with = 4 or 6. On swelling aqueous LLC mesophases with up to 35 wt % -decane, we demonstrate that odd-carbon linked surfactants ( = 3 or 5) form G and normal double diamond (D) phases over wide water concentration windows with = 22-100 °C.
View Article and Find Full Text PDFJ Colloid Interface Sci
July 2019
CIQUP, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal. Electronic address:
Surfactants have been widely employed to debundle, disperse and stabilize carbon nanotubes in aqueous solvents. Yet, a thorough understanding of the dispersing mechanisms at molecular level is still warranted. Herein, we investigated the influence of the molecular structure of gemini surfactants on the dispersibility of multiwalled carbon nanotubes (MWNTs).
View Article and Find Full Text PDFLangmuir
December 2015
Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education , Jinan, 250100, China.
The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface.
View Article and Find Full Text PDFCarbohydr Polym
November 2015
Department of Chemistry, University of Kashmir, Srinagar 190006, J&K, India. Electronic address:
The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.
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