Dependence of aggregate morphology on structure of dimeric surfactants

Zana, R.; Talmon, Yeshayahu

doi:10.1038/362228a0

Cited by 517 publications

(405 citation statements)

References 19 publications

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“…The micelle size and shape data have been obtained using a combination of cryo-TEM imaging, time-resolved fluorescence quenching (TRFQ), and small-angle neutron scattering (SANS) experiments. Gemini surfactants with short spacers, 10-3-10,2 Br − and 12-3-12,2 Br − , form elongated rods or threadlike micelles at concentrations where the corresponding monomeric surfactant forms only spheres [12,13]. The gemini molecule 16-3-16,2 Br − also forms aggregates of lower curvature compared to its monomeric analog, as cryo-TEM imaging revealed vesicles, bilayer membrane fragments, and threadlike micelles [12].…”

Section: Introductionmentioning

confidence: 99%

Micelle formation and CMC of gemini surfactants: a thermodynamic model

Camesano

Nagarajan

2000

Colloids and Surfaces A: Physicochemical and Engineering Aspect

142

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Gemini surfactants possess a structure resembling a pair of conventional single chain surfactants covalently connected by a spacer. The spacer can vary in length and chemical structure. In this paper, the aggregation behavior of gemini surfactants is examined on the basis of a free energy model developed by extending our theory for conventional surfactants. Free energy contributions beyond those considered for conventional surfactants arise because of the spacer. They originate from the fact that (a) the spacer shields the hydrophobic core of the aggregate from contact with water, (b) the spacer constrains the distance between the head groups, thus imposing non-uniformity in charge distribution at the aggregate surface, (c) the spacer prevents the two linked tails from having a packing conformation inside the micelle identical to that of analogous unlinked single chain surfactants, and (d) the spacer can be partially buried inside the micelle core provided its length and the molecular interactions allow it. Illustrative calculations for gemini surfactants with tail lengths of 5 -16 carbon atoms and various spacers are discussed here. The spacers considered include the polymethylene chain and a combination of polymethylene chain with NCH 3 , O, S, and aromatic groups. The predicted critical micelle concentration (CMC), micelle aggregation number, sphere-to-rod transition parameter (K) and shape of aggregates are compared with available experimental data. A comparative analysis of the magnitude and shape dependence of the individual contributions to the free energy shows that the nonuniform charge distribution at the aggregate surface and the additional packing constraint on the tails, both originating from the short length of the spacer, play a central role in determining the equilibrium shape of the aggregates.

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Section: Introductionmentioning

confidence: 99%

Micelle formation and CMC of gemini surfactants: a thermodynamic model

Camesano

Nagarajan

2000

Colloids and Surfaces A: Physicochemical and Engineering Aspect

142

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“…In aqueous solution of a gemini surfactant, Krafft point (Kp) and critical micelle concentration (CMC) are lower and the interfacial activity is higher compared to the corresponding monosurfactant. Therefore, gemini surfactants are more superior surfactants, thus several researchers [9] [10] [11] [12] have investigated them thoroughly. Moreover, gemini surfactants have two hydrophobic alkyl chains, thus they are better candidates to prepare and investigate model membranes for applications in drug delivery systems (DDS) [12] [13] [14].…”

Section: Introductionmentioning

confidence: 99%

“…Among various surfactants, "gemini" surfactant essentially has a structure in which two general or common category monosurfactants having one hydrophobic and one hydrophilic moiety are connected by a spacer group such as an alkyl chain or a peptide group [9] [10] [11]. In aqueous solution of a gemini surfactant, Krafft point (Kp) and critical micelle concentration (CMC) are lower and the interfacial activity is higher compared to the corresponding monosurfactant.…”

Section: Introductionmentioning

confidence: 99%

Surface Properties of Novel Surfactant, Dihexadecyl Gemini Phosphate, Monolayers on Water Surface by Dropping Method

Kobayashi¹,

Amano²,

Taga³

et al. 2017

JBPC

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We have synthesized first novel dihexadecyl phosphate (DHGP-n) gemini surfactants containing alkyl chain ((C n H 2n ); n = 3, 4, 5, and 6) spacers. Surfactants were used to form monolayers on water surface. Surface tension measurement (STm), Brewster angle microscopy (BAM), and density functional theory (DFT) calculation were used to investigate these monolayers. Surface pressure (π) and molecular area (A); π-A isotherm curves of all DHGP-n gemini surfactants showed a gradual increase in surface pressure without any break points in the curves, confirmed the formation of liquid-expand (LE) type monolayers. BAM observations also supported the STm results. Limited molecular area (A 0 ) of these monolayers depended on the spacer of gemini surfactants without spacer n = 4. Longer alkyl chain spacer in the series had higher value of A 0 in π-A isotherm plots. In the series, A 0 of spacer n = 4 was smallest among A 0 values of other spacers. Density functional theory (DFT) method calculation also confirmed π-A isotherm curves pattern of these surfactants. Calculation showed that both odd and even numbers and length of the alkyl chain spacer influenced the structure of DHGP-n monolayer formation on the water surface.

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“…Compared with their monomeric counterparts, gemini surfactants usually have favorable surface activities, lower critical micelle concentration (CMC), better wetting ability, enhanced dispersion, higher foaming stability, and unique rheological responses [1,2]. As a result of these desirable properties, gemini surfactants have attracted considerable attention in both academic research and practical applications [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

et al. 2008

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A series of new dimeric surfactants, twin-tailed gemini surfactants, 2(12)-s-2(12), were successfully prepared and characterized, and their monolayer films investigated by the measurement of surface pressure-area (π-A) and surface pressure-time (π-t) isotherms at the air/water interface by a Langmuir film balance. Compared to their monomeric counterparts, their collapse pressure (g collapse ) is smaller, whilst all the molecular area parameters are larger. The limited area (A limited ) and the initial area (A initial ) of these twin-tailed gemini surfactants change with increasing spacer length s, and the surface pressure decreases with increasing time. It was also found that the higher the initial surface pressure, the larger the attenuation.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Dependence of aggregate morphology on structure of dimeric surfactants

Cited by 517 publications

References 19 publications

Micelle formation and CMC of gemini surfactants: a thermodynamic model

Micelle formation and CMC of gemini surfactants: a thermodynamic model

Surface Properties of Novel Surfactant, Dihexadecyl Gemini Phosphate, Monolayers on Water Surface by Dropping Method

Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

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