Effect of Hydrophobic Chain Length of Surfactants on Enthalpy−Entropy Compensation of Micellization

Chen, Li‐Jen; Lin, Shi‐Yow; Huang, Chiung-Chang

doi:10.1021/jp9804345

Cited by 317 publications

(242 citation statements)

References 27 publications

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“…The temperature corresponding to the minimum CMC depends on the type of surfactant. Generally speaking, the minimum occurs around room temperature for the case of hydrocarbon ionic surfactants, whereas the corresponding temperature for nonionic surfactants is rather high (12,13). The behavior of the temperature dependence of CMC observed with the present phosphate-type hybrid surfactants and with other hybrid surfactants (7) is quite close to that of conventional ionic hydrocarbon surfactants.…”

Section: Micelle Formation Of Phosphate-type Hybrid Surfactants In Aqsupporting

confidence: 55%

Micelle Formation of Phosphate-Type Hybrid Surfactants in Aqueous Solution

et al. 2005

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Micelle formation in aqueous solution of novel hybrid surfactants with phosphate head group was investigated. The critical micelle concentrations (CMC) were determined as a function of temperature by surface tension measurements. The results of electrical conductivity measurements were analyzed according to the mixed electrolyte model of the micellar solution to estimate the micellar aggregation number and the degree of counter-ion binding on the micelle. Thermodynamic parameters for the micelle formation were estimated on the basis of these results. Discussion is given on the micelle formation of the present surfactant species comparing with the sulfonate-type hybrid surfactants.

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Section: Micelle Formation Of Phosphate-type Hybrid Surfactants In Aqsupporting

confidence: 55%

Micelle Formation of Phosphate-Type Hybrid Surfactants in Aqueous Solution

et al. 2005

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“…According to the packing parameter theory, a single-tailed surfactant tends to form spherical micelles, while a double-tailed surfactant leads to a bilayer structure in aqueous solution. Generally, a systematical examination of the effect of the surfactant head group on the molecular aggregates has some difficulties compared with that of the hydrophobic tail group, except for some nonionic surfactants with polyethylene or polysaccharide units [3][4][5][6][7][8][9][10][11][12][13][14]. Another exception is the amino acid-type surfactant system [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Effect of the side chain of N-acyl amino acid surfactants on micelle formation: An isothermal titration calorimetry study

Ohta

Toda

Morimoto

et al. 2008

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The enthalpy of micelle formation, critical micelle concentration (CMC), and aggregation number of micelles for seven amino acid type surfactants, sodium-L-glutaminate (C12Gln), and -L-threoninate (C12Thr), were obtained at three temperatures ranging from 288.15 to 308.15 K by isothermal titration calorimetry. The enthalpies of micelle formation for these surfactants were positive at 288.15 K and decreased with increasing temperature to ultimately become negative above 308.15 K. The CMC of the amino acid surfactants decreased monotonously with increasing hydrophobicity of the amino acid residue without exception, while with the exception of the C12Phe system, the enthalpy of micelle formation increased. The micellization behavior of C12Phe also deviated from that of other amino acid systems in terms of the heat capacity and the aggregation number. These results suggest the presence of a strong intra-micelle interaction between the side chains of phenylalanine.

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“…This means that the "dehydration" part of the clouding process may follow the same mechanism for all the systems studied [34]. Huang et al found that the compensation plots for the micellization of three nonionic surfactants (C 12 E 4 , C 12 E 5 and C 12 E 6 ) in aqueous solution all coincided on a single straight line, which implies that both the "desolvation" and "chemical" part of the process of micellization are independent of the size of the hydrophilic group of surfactants [35,36]. The calculated value of T C for pure water was 325 ± 5 K and for 1 M NaCl it was 310 ± 4 K. It is clear that the presence of salt reduce the value of T C , thus indicating that less energy is required to induce phase separation in the presence of salt.…”

Section: Enthalpy-entropy Compensationmentioning

confidence: 99%

An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

Hierrezuelo

Molina-Bolı́var

Ruiz

2014

Entropy

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Abstract:The main goal of this paper was to examine the effect of the hydrophilic surfactant headgroup on the phase behavior of non-ionic surfactant mixtures. Four mixed systems composed of an ethoxylated plus sugar-based surfactants, each having the same hydrophobic tail, were investigated. We found that the hydrophilicity of the surfactant inhibits the tendency of the system to phase separate, which is sensitive to the presence of NaCl. Applying a classical phase separation thermodynamic model, the corresponding energy parameters were evaluated. In all cases, the parameters were found to depend on the type of nonionic surfactant, its concentration in the micellar solution and the presence of NaCl in the medium. The experimental results can be explained by assuming the phase separation process takes place as a result of reduced hydration of the surfactant headgroup caused by a temperature increase. The enthalpy-entropy compensation plot exhibits excellent linearity. We found that all the mixed surfactant systems coincided on the same straight line, the compensation temperature being lower in the presence of NaCl.

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Effect of Hydrophobic Chain Length of Surfactants on Enthalpy−Entropy Compensation of Micellization

Cited by 317 publications

References 27 publications

Micelle Formation of Phosphate-Type Hybrid Surfactants in Aqueous Solution

Micelle Formation of Phosphate-Type Hybrid Surfactants in Aqueous Solution

Effect of the side chain of N-acyl amino acid surfactants on micelle formation: An isothermal titration calorimetry study

An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

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