Etude par viscosité et autodiffusion de solutions aqueuses de divers n-alkyl-benzènesulfonates

Kamenka, N.; Chorro, M.; Fabre, H.; Lindman, Björn; Rouvière, J.; Cabos, C.

doi:10.1007/bf01474106

Cited by 15 publications

(6 citation statements)

References 17 publications

(9 reference statements)

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“…Thus, also the interaction between surfactants and the polymer hydrophobic tails seems to be weaker with cationic than with anionic surfactants. Possibly part of the explanation can be attributed to the same reasons that give higher cmc's of cationic surfactants as compared to anionic of the same chain length (see Table ). , These studies indicate that cationic surfactants in general have a weaker tendency to assemble in aggregates than their anionic analogues. Another difference is that, compared to anionic surfactants, η* 0.1Hz attains higher values at high surfactant concentrations with cationic surfactants (for both EHEC and HM-EHEC systems).…”

Section: Resultsmentioning

confidence: 85%

Effect of Hydrophobic Modification of a Nonionic Cellulose Derivative on the Interaction with Surfactants. Rheology

1997

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The interactions between various surfactants (anionic, cationic, and nonionic) and a nonionic ethyl(hydroxyethyl)cellulose (EHEC) polymer or a hydrophobically modified analogue (HM-EHEC) have been examined. The study has been performed as a comparative investigation between the hydrophobically modified polymer and the unmodified parent polymer using rheology. The rheological results have been analyzed with the aid of a simple modified Maxwell model. Information about the low-frequency behavior was extracted from this model, and the rheological features were presented in terms of the complex viscosity and a characteristic relaxation time. In the presence of an ionic surfactant, the rhelogical measurements revealed significant polymer/surfactant interaction for both EHEC and HM-EHEC, but the interaction peak, observed in the different rheological quantities, was more pronounced and located at a lower surfactant concentration for the hydrophobically modified polymer. In the presence of a nonionic surfactant, the polymer/surfactant interaction was weaker. By considering the temperature effect, an important difference in the polymer dynamics between the hydrophobically modified polymer and the unmodified analogue was established. The hydrophobically modified polymer shows a normal temperature dependency, while the motion of the unmodified analogue is slowed down with increasing temperature. The finding for the unmodified polymer is attributed to increased polymer/polymer attractions with an increased temperature. It has also been shown that the hydrophobically modified polymer has features regarding the formation and breakdown of the polymer/surfactant complex in common with other hydrophobically modified polymers (both nonionic and ionic). At a certain surfactant concentration the network starts to lose its connectivity, however, because of an increased surfactant aggregation number of the mixed micelles, the breakdown process is postponed when the surfactant chain length is increased.

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Section: Resultsmentioning

confidence: 85%

Effect of Hydrophobic Modification of a Nonionic Cellulose Derivative on the Interaction with Surfactants. Rheology

1997

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“…The same calculations of thermodynamic functions were then applied to the data of c.m.c. reported by other authors [17][18][19][20][21][22][23][24][25][26][27][28] for any kind of surfactants. The values of n w calculated from the experimental values reported by different authors for the same compound are, however, rather different.…”

Section: Resultsmentioning

confidence: 86%

Thermodynamics of micelle formation in water, hydrophobic processes and surfactant self-assemblies

Fisicaro

Compari

Duce

et al. 2008

Phys. Chem. Chem. Phys.

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The critical micelle concentration (c.m.c.) for four cationic surfactants, alkyl-trimethyl-ammonium bromides, was determined as a function of temperature by conductivity measurements. The values of the standard free energy of micellisation DeltaG degrees(mic) at different temperatures were calculated by using a pseudo-phase transition model. Then, from the diagram (-DeltaG degrees(mic)/T)=f(1/T), the thermodynamic functions DeltaH(app) and DeltaS(app) were calculated. From the plots DeltaH(app)=f(T) and DeltaS(app) = f(ln T) the slopes DeltaC(p) = n(w(H))C(p,w) and DeltaC(p)=n(w(S))C(p,w) were calculated, with the numbers n(w(H)) and n(w(S)) negative and equal and therefore defined simply as n(w). The number n(w)<0, indicating condensed water molecules, depends on the reduction of cavity that takes place as a consequence of the coalescence of the cavities previously surrounding the separate aliphatic or aromatic moieties. The analysis, based on a molecular model consisting of three forms of water, namely W(I), W(II), and W(III), respectively, was extended to several other types of surfactants for which c.m.c. data had been published by other authors. The results of this analysis form a coherent scheme consistent with the proposed molecular model. The enthalpy for all the types of surfactant is described by DeltaH(app)= -3.6 + 23.1xi(w)-xi(w)C(p,w)T and the entropy by DeltaS(app)= +10.2+428xi(w)-xi(w)C(p,w) ln T where xi(w)= |n(w)| represents the number of molecules W(III) involved in the reaction. The term Deltah(w)= +23.1 kJ mol(-1) xi(w)(-1) indicates an unfavourable endothermic contribution to enthalpy for reduction of the cavity whereas the term Deltas(w)= +428 J K(-1) mol(-1) xi(w)(-1) represents a positive entropy contribution for reduction of the cavity, what is the driving force of hydrophobic association. The processes of non polar gas dissolution in water and of micelle formation were found to be strictly related: they are, however, exactly the opposite of one another. In micelle formation no intermolecular electronic short bond is formed. We propose, therefore, to substitute the term "hydrophobic bond" with that of "hydrophobic association".

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“…This finding is in agreement with the association constants found for a similar surfactant n-octylbenzenesulfonate. 65 It is worth coming back to the specific role of the surfactant headgroup. While in the case of alkylsulfates the previously mentioned series is found, different results are observed in the case of phospholipids.…”

Section: Discussionmentioning

confidence: 99%

Specific Alkali Cation Effects in the Transition from Micelles to Vesicles through Salt Addition

et al. 2007

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The transition of ionic micelles to vesicles with added salts is explored in this paper. The catanionic surfactant solution was comprised of sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) with an excess of SDS. The micellar size increased with concentration for all salts. No anion specificity was found, probably because of the excess of SDS. However, when the cation of the added salt was varied, large differences were observed in the hydrodynamic radii of the aggregates. A classification of the cations according to their ability to increase the measured hydrodynamic radii follows a Hofmeister series. The change in aggregate size can be explained by modified counterion binding and dehydration of the surfactant headgroups.

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Etude par viscosité et autodiffusion de solutions aqueuses de divers n-alkyl-benzènesulfonates

Cited by 15 publications

References 17 publications

Effect of Hydrophobic Modification of a Nonionic Cellulose Derivative on the Interaction with Surfactants. Rheology

Effect of Hydrophobic Modification of a Nonionic Cellulose Derivative on the Interaction with Surfactants. Rheology

Thermodynamics of micelle formation in water, hydrophobic processes and surfactant self-assemblies

Specific Alkali Cation Effects in the Transition from Micelles to Vesicles through Salt Addition

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