The pH Change with Concentration of Aqueous Solutions of Metal Dodecyl Sulfates

Matuura, Ryôhei; Satake, Iwao; Iwamatsu, Ichiro; Hosokawa, Shizuko

doi:10.1246/bcsj.35.1050

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…It is attributed to that as the stirring was stopped, the coalescence of droplets or air bubbles took place, thus the vanished interface released H + . Other fact is that pH increased with the increase of SDS concentration in water [45,47, 48] . Taking into account the high concentration of protons at the interface of water/air, [49] the affinity of hydrophobic chain for protons shows a strong relation with the decrease of surface tension.…”

Section: Resultsmentioning

confidence: 99%

“…Other fact is that pH increased with the increase of SDS concentration in water. [45,47,48] Taking into account the high concentration of protons at the interface of water/air, [49] the affinity of hydrophobic chain for protons shows a strong relation with the decrease of surface tension. Moreover, this proposition provides a qualitative answer to the problem annoying researchers for decades, [50] namely the extreme difference of polyethylene glycol (PEG) and polyformaldehyde (POM) in the water solubility.…”

Section: Propositionmentioning

confidence: 99%

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Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Xia

Qian

et al. 2021

ChemistrySelect

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In this paper, the hydrophobic effect or hydration of hydrophobe was firstly introduced into the mechanism of polystyrene particles formation. Negatively charged surface of hydration shell was proposed due to the ordered structure of water molecules. Consequentially the concentration of hydrophobic chains depended on pH because protons destroyed the hydration shell, thereby extruded hydrophobic chains from the H-bonds networks. The soap-free emulsion polymerization of styrene by using AIBN (azodiisobutyronitrile) and KPS (Potassium Persulfate), respectively was performed at various pHs. It was proved that protons played a crucial role on the formation of PSt (polystyrene) particles. By using AIBN, particles were not prepared at pH 2.0 (HAc), pH 4.0 (HCl) and pH 2.0 (HCl), whereas by using KPS, particles were obtained regardless to pH. It indicated that anions of sulfate greatly enhanced the tolerance of hydration shell to the suffering from protons. Meanwhile, the roles of polymerization in the monomer phase, aqueous phase and growing particles were elucidated. By using AIBN, ca. 30 % PSt with M n (Numeral average molecular weight) = 300-1500 formed in the monomer phase at pH 6.8, which dissolved in water at pH 8.0 and pH 10.0. By using KPS, ca. 20 % and 30 % conversion of St were found in the aqueous phase at pH 2.0 (HCl) and pH 10.0 (NaOH), respectively. At pH 2.0 (HCl), oligomers generated in the aqueous phase were protonated, whereas at pH 10.0 (NaOH), they were soluble due to the seriously suppressed dissociation of water. At other pHs, oligomers captured protons, thereby relieved particles and interface from the suffering of protons. As the concentration of oligomers increased, oligomers precipitated to form clusters due to the increase of average number of protons on the surface of oligomers hydration shell, which successively incorporated into the growing particles, thus enlarged PDI (Polydispersity index) of MW (Weight-average molecular weight) distribution in particles. By using AIBN, owing to the limited partition of AIBN in the interfacial layer of St phase, the flat-roof peaks of GPC curves were observed, namely that the weight fraction of M i was constant. It implies that the freeradicals are living in the growing particles.

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Section: Resultsmentioning

confidence: 99%

Section: Propositionmentioning

confidence: 99%

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Xia

Qian

et al. 2021

ChemistrySelect

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Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate and lauryl alcohol. Part III: The effect of impurities and additives on pH and electrical conductance of premicellar and micellar solutions of sodium lauryl sulphate

1979

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Experimental measurements of the pH, electrical conductance and Kraft temperatures were made for a number of commercially available and purified samples of sodium lauryl sulphate for a wide range of surfactant concentrations in aqueous solutiin at 25°C. The efect of lauryl alcohol and sodium chloride on the pH and electrical conductance was also studied. The effects of type of electrodes, sequence of measurements, the memory effect, mixing and carbon dioxide were explored for the pH measurements. The results show that pH is a convenient and reliable method for the determination of critical micelle concentration (CMC) of ionic surfactants. The pH versus concentration data can also be used to uniquely identify the presence of contaminants or species other than pure sodium lauryl sulphate in that discontinuities occur in the data at unique concentrations so that identification of the contaminant is easy. High concentration discontinuities are identified and are attributed to individual or mixture CMC values. Anomalies in the data occur for concentrations less than 0.05 wt.% and especially around 0.01 to 0.02 wt.% for pure sodium lauryl sulphate solutions. Data are also given that show the effects of aging. Data reported in the literature for the pH, electrical conductance and Kraft temperature are compared.

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Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate: Part IV: Dilute aqueous solution behavior by electron spin resonance studies and by pH and surface tension measurements

1980

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The electron spin resonance spectrum of the nitroxide label 2,2,6,6 – TetraMethyl – 4 – Piperidone – Oxide (TEMPO) has been investigated in aqueous solutions of a purified and commercially available impure samples of sodium lauryl sulphate (NaLS) for a wide range of concentrations. The spectra were recorded at 24°C as a function of surfactant concentration. The reorientational correlation times Tθ of the TEMPO label in aqueous solutions were calculated using the Kivelson's theory. Using the Tθ data qualitative analysis has been carried out in an attempt to understand the microscopic effects produced by the hydrophobic part of the surfactant on the water structure and the hydrophobic‐hydrophobic interactions in water. Four major discontinuities in the τθ results have been identified with the purified NaLS system. They are found to occur at NaLS concentrations of 0.008 wt.%, 0.015 wt.%, 0.23 and 1.73 wt.%. The latter two concentrations represent the first and the second critical micelle concentration (CMC) of the surfactant while the first two concentrations reveal the existence of premicellar association and dissociation processes, respectively. These discontinuities have been also confirmed by the pH data and by surface tension results from the du Noüy ring method. The effect of addition of lauryl alcohol and sodium chloride on τθ values was also studied. The additive action has been found to produce an additional discontinuity, corresponding to the mixture CMC, in the τθ versus concentration plot. Analysis of other effects such as solution aging and hydrolysis of NaLS are also included. The applicability of the spin labelling technique for the study of aqueous solution behavior of NaLS is discussed by comparing data reported in the literature.

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The pH Change with Concentration of Aqueous Solutions of Metal Dodecyl Sulfates

Cited by 3 publications

References 2 publications

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Roles of Proton in the Formation of Particles: Soap‐free Emulsion Polymerization of Styrene using AIBN and Potassium Persulfate as Initiators

Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate and lauryl alcohol. Part III: The effect of impurities and additives on pH and electrical conductance of premicellar and micellar solutions of sodium lauryl sulphate

Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate: Part IV: Dilute aqueous solution behavior by electron spin resonance studies and by pH and surface tension measurements

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