An electroconductivity study on degree of counterion binding or dissociation of a-sulfonatomyristic acid methyl ester micelles in water as a function of temperature

Sugihara, Gohsuke; Nakamura, Atsushi; Nakashima, Takayuki; Araki, Yau-Ichi; Okano, Tamon; Fujiwara, Masami

doi:10.1007/s003960050149

Cited by 43 publications

(54 citation statements)

References 20 publications

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“…In an early study of 12-s-12 and 16-s-16 dimers the micelle ionization degree was obtained from the K vs C plots and taken as (41). However, it has been recently shown that this method yields values of α that are overestimated because the conductivity of the micelles is underestimated (42). The reported values of α have therefore been discarded and the conductivity data reanalyzed using the method of Evans (43).…”

Section: Discussionmentioning

confidence: 99%

Alkanediyl-α,ω-bis(dimethylalkylammonium bromide) Surfactants

Zana

2002

Journal of Colloid and Interface Science

146

100

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Section: Discussionmentioning

confidence: 99%

Alkanediyl-α,ω-bis(dimethylalkylammonium bromide) Surfactants

Zana

2002

Journal of Colloid and Interface Science

146

100

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“…In addition, the α value, 0.51, obtained for SDMS is smaller than that value, 0.64, obtained by the slope below and above the cmc from the plot of specific conductance vs. molar concentration (1), because the conductivity of the micelles is underestimated (29). Figures 5A and 5B show the potentiometric titration curves for 212 and SDMA.…”

Section: A B Cmentioning

confidence: 95%

Micelle ionization degree of anionic gemini surfactant having N,N‐dialkylamide and carboxylate groups

Tsubone¹,

Ghosh

2003

J Surfact & Detergents

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The critical micelle concentration (cmc) behavior in aqueous NaCl solutions of the anionic gemini surfactant N, N'-ethylenebis(sodium N-dodecanoyl-β-alanate), (CH 2 ) 2 [N-(COC 11 H 23 )CH 2 CH 2 (CO 2 Na)] 2 (212), having N,N-dialkylamide and carboxylate groups in a molecule was investigated to measure the value of micelle ionization degree (α). For comparison, the behavior of sodium N-dodecanoyl-N-methyl-β-alanate (SDMA), a monomer corresponding to 212, also was investigated. The α value obtained from the Corrins-Harkins plot for 212 is 0.97 when [Na + ] ≤ 0.025 M and the value for SDMA is 0.51 when [Na + ] ≤ 0.1 M. That the α for 212 is larger than that for SDMA reflects the higher pK a1 value for 212 than the pK a value of SDMA. For 212, when [Na + ] ≤ 0.025 M the amount of Na + released during micellization is so large that the Na + concentration above the cmc is almost equal to that below the cmc, and therefore 212 nearly behaves as a nonionic surfactant.Paper no. S1330 in JSD 6, 225-229 (July 2003).KEY WORDS: Anionic gemini surfactant, Corrin-Harkins plot, degree of counter-ion binding, micelle ionization degree.Unusual interfacial behaviors are shown by two anionic surfactants, sodium N-dodecanoyl-N-methyl-β-alanate (SDMA) and sodium N-dodecanoylsarcosinate (SDSA), having N,Ndialkylamide and carboxylate groups, in comparison with those of sodium N-dodecanoyl-N-methyltaurate (SDMT), having a sulfonate group instead of a carboxylate group, and sodium decyloxyacetate (SDOA), containing an ether oxygen instead of an N-methyl adjacent to the methylenecarboxylate group (1). The unusual behaviors were found to be due to the simultaneous presence of the N,Ndialkylamide and carboxylate groups in the same molecule. Namely, the increasing order of conductance/surface tension critical micelle concentration (cmc) ratios is SDOA < SDMT < SDSA < SDMA. This order is the same as those of the parameters, A min (the minimum area occupied by the surfactant molecule at the air/water interface) and cmc/C 20 ratio (a measure of the factors inhibiting micellization relative to adsorption at the air/water interface), implying that there is a steric factor inhibiting micellization for the compounds having N,N-dialkylamide and carboxylate groups. The same order of increase in pH with surfactant concentration in the vicinity of the cmc appears to indicate H-bonded interaction between amide and protonated carboxylate groups. Thus, anionic surfactants having N,N-dialkylamide and carboxylate groups release Na + in micellization.In the past decade, a new type of surfactant called gemini surfactants has attracted considerable interest (2-19), since these compounds have much smaller cmc values and much greater efficiency in reducing surface tension than expected. They have two hydrophobic chains and two hydrophilic head groups in the molecule. The gemini surfactants are the subject of more studies, because of the extraordinary surface activity (3,9,13,14,19,20).For several years, Tsubone and coworkers have studied the anionic gemini surfa...

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“…A reported set of α values was obtained assuming α equal to the ratio of the slopes of the specific conductivity vs concentration plot above and below cmc (4). It has been recently shown that the values of α so obtained are overestimated (46). These values have therefore been discarded and the conductivity data reanalyzed using the method of Evans (47) that yields more realistic values of α.…”

Section: Thermodynamics Of Micellization Of 12-s-12 Surfactantsmentioning

confidence: 97%