Viscometric studies on the methyl cellulose-sodium dodecyl sulphate complex in aqueous solution

Sakamoto, Noriyuki

doi:10.1016/0032-3861(87)90419-8

Cited by 8 publications

(5 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is assumed 6,9,16 that this maximum reflects the saturation of binding to the polymer followed by the formation of normal free micelles in the solution and possibly a decrease in ionic (DS - ) activity . A similar maximum in adsorption isotherms has been observed and reported for several aqueous salt-free polymer/surfactant systems such as the EHEC/SDS/water, ,, the methyl cellulose (MC)/SDS/water, , the HPMC/SDS/water, the poly(vinyl alcohol) (PVA)/SDS/water, the poly(vinylpyrrolidone) (PVP)/SDS/water, and the PEO/SDS/water systems (results shown in Figure ).…”

Section: Resultsmentioning

confidence: 58%

Temperature Effects on the Interactions between EHEC and SDS in Dilute Aqueous Solutions. Steady-State Fluorescence Quenching and Equilibrium Dialysis Investigations

et al. 1996

View full text Add to dashboard Cite

The interaction between the hydrophobic, nonionic cellulose derivative ethyl hydroxyethyl cellulose (EHEC; fraction CST-103) and the anionic surfactant sodium dodecyl sulfate (SDS) has been studied as a function of temperature from 20 to 50 °C in dilute aqueous solutions, i.e. a polymer concentration slightly below the critical overlap concentration (c*) and a surfactant concentration up to three times the normal critical micelle concentration (cmc). Methods utilized in this investigation include equilibrium dialysis and steady-state fluorescence quenching. The results show that the average aggregation numbers of the polymer-bound SDS clusters decrease with an increase in temperature although the magnitude of the effect is composition dependent and is most pronounced for compositions which give the largest cluster sizes. The adsorption of SDS to EHEC shows a break-point at an intermediate value of the adsorption isotherm above which the cooperativity increases. This break-point diminishes and disappears, i.e. the cooperativity decreases, as the temperature increases up to 50 °C. It is suggested that the mechanism responsible for these two steps in the adsorption process is at first adsorption of SDS to aggregated EHEC chains and then to a mainly deaggregated state of EHEC. The critical surfactant concentration where the adsorption to the polymer starts seems to be slightly shifted toward lower values as the temperature is raised from 20 to 50 °C. To summarize the results, the interaction between EHEC and SDS gets more intensive as the temperature is raised. Two fluorophore/quencher pairs, which previously have been used for determination of average aggregation numbers in aqueous surfactant and polymer−surfactant systems utilizing the steady-state fluorescence quenching technique, are compared. A good agreement between the two pairs is reported. Reference measurements of average aggregation numbers and adsorption isotherms for the PEO/SDS/water system are also given.

show abstract

Section: Resultsmentioning

confidence: 58%

Temperature Effects on the Interactions between EHEC and SDS in Dilute Aqueous Solutions. Steady-State Fluorescence Quenching and Equilibrium Dialysis Investigations

et al. 1996

View full text Add to dashboard Cite

show abstract

“…Bulk viscosity is one of the main methods used for the characterization of polymer−surfactant interactions, and it is especially useful when studying systems where strong interactions exist such as the interaction between some nonionic cellulose ethers and SDS. ,,,, It has been shown 7 that the hydrodynamic behavior of an aqueous bulk solution of EHEC and SDS depends critically on both polymer and surfactant concentration. Figure presents the bulk viscosity behavior, here expressed as η sp / c , as a function of the total SDS concentration and for three different EHEC concentrations.…”

Section: Resultsmentioning

confidence: 99%

Microviscosity in Clusters of Ethyl Hydroxyethyl Cellulose and Sodium Dodecyl Sulfate Formed in Dilute Aqueous Solutions As Determined with Fluorescence Probe Techniques

Evertsson

Nilsson

1997

Macromolecules

View full text Add to dashboard Cite

The microviscosity has been measured in dilute aqueous solutions of ethyl hydroxyethyl cellulose (EHEC) and sodium dodecyl sulfate (SDS) by utilizing three steady-state fluorescence probe techniques: intramolecular excimer formation by 1,3-di(1-pyrenyl)propane (P3P), fluorescence depolarization of perylene, and intramolecular rotational relaxation about bonds with (p-(dimethylamino)benzylidene)malononitrile (BMN). Results obtained by the three techniques are compared. They all detect qualitatively the same behavior with a well-developed maximum in microviscosity and rigidity of the EHEC/SDS clusters formed at a surfactant concentration close to or slightly higher than the critical surfactant concentration where adsorption to the polymer starts. The EHEC/SDS clusters have, independent of composition, higher microviscosities than ordinary SDS micelles. The microviscosity is also compared with other EHEC/SDS/water system features such as the bulk viscosity, the actual adsorption isotherm, the average aggregation numbers, and the micropolarity as sensed by pyrene of the EHEC/SDS clusters formed. The maximum in microviscosity corresponds to a rather low degree of SDS adsorption to EHEC (≈0.5 mmol of SDS per gram of EHEC) and a low aggregation number (≈10) where the polymer content of each polymer-bound surfactant cluster is high. It coincides (according to the surfactant concentration) with a maximum in bulk viscosity for polymer concentrations higher than the critical overlap concentration (c*). It is suggested that the maximum in bulk viscosity is due to a three-dimensional network of polymer and cluster tie points while the maximum in microviscosity is related to a high content of hydrophobic polymer segments which stabilizes the surfactant clusters.

show abstract

“…The adsorption isotherm for a polymer/surfactant/water system can be determined by several methods such as equilibrium dialysis, − NMR, conductivity, − isotherm titration microcalorimetry, ,,, and potentiometry using ion specific electrodes. − Some of those are, unfortunately, unable to give data at higher surfactant concentrations, especially after saturation of the polymer chain. , In this paper, the thermodynamics of the interaction equilibrium is explored using dialysis experiments in a temperature region from room temperature up to the cloud point. The method has the advantage that the equilibrium can be studied up to compositions far above the point of saturation and that the redistribution of surfactant (expressed in moles per mass unit of polymer) is obtained directly.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Properties of Surfactant/Polymer/Water Systems with Respect to Clustering Adsorption and Intermolecular Interaction as a Function of Temperature and Polymer Concentration

1997

View full text Add to dashboard Cite

This investigation forms part of a more extensive physicochemical study of the interaction of amphiphiles with different polymers, partially as a background for a better understanding of the function of pharmaceutical excipients. For the ethyl hydroxyethyl cellulose (EHEC)/sodium dodecyl sulfate (SDS)/water system, the dialysis equilibrium between a solution containing polymer and a solution not containing polymer has been investigated over a composition interval of the amphiphile ranging from zero up to well above cmc and for the polymer from zero up to slightly above the concentration of critical overlap. It is found that the amphiphile begins to redistribute preferentially to the polymer at a “foot point” (critical aggregation concentration) concentration of 2 mM SDS, rises to a maximum value at an SDS concentration most likely corresponding to the onset of formation of normal micelles in bulk, and then decreases. The maximum adsorption corresponds to approximately two DS- ions per structural unit of the polymer. It is proposed that the results observed could be interpreted in terms of a redistribution of surfactant to the polymer coil regions leading to locally enhanced surfactant concentration, cluster formation, and adsorption. In combination with polymer reconformation this model suggests an explanation of some specific effects observed on this system: the increase in average cluster size with increasing polymer concentration, the marked decrease in intrinsic viscosity at the onset of surfactant adsorption combined with a strong hydrodynamic interaction (high value of the Huggins' constant), and the considerable increase in macroscopic viscosity during the first phase of adsorption. The decrease in specific adsorption after the maximum probably derives from changes in DS- ion activity and saturation of the polymer, as well as the formation of normal micelles. Temperature is found to have only a small influence on the redistribution in an interval from room temperature up to the cloud point. The correction for the Donnan effect is discussed and results from conductometric measurements are used to calculate the degree of dissociation of surfactant in the micellar clusters.

show abstract

Viscometric studies on the methyl cellulose-sodium dodecyl sulphate complex in aqueous solution

Cited by 8 publications

References 23 publications

Temperature Effects on the Interactions between EHEC and SDS in Dilute Aqueous Solutions. Steady-State Fluorescence Quenching and Equilibrium Dialysis Investigations

Temperature Effects on the Interactions between EHEC and SDS in Dilute Aqueous Solutions. Steady-State Fluorescence Quenching and Equilibrium Dialysis Investigations

Microviscosity in Clusters of Ethyl Hydroxyethyl Cellulose and Sodium Dodecyl Sulfate Formed in Dilute Aqueous Solutions As Determined with Fluorescence Probe Techniques

Thermodynamic Properties of Surfactant/Polymer/Water Systems with Respect to Clustering Adsorption and Intermolecular Interaction as a Function of Temperature and Polymer Concentration

Contact Info

Product

Resources

About