The Absence of Conventional Polymer-Surfactant Interaction between Sodium Monodecyl Phosphate and Poly(ethylene Oxide): Conductivity and Kinetic Evidence

The Role of the Carboxylate Head Group in the Interaction of Sodium Dodecanoate with Poly(ethylene oxide) Investigated by Electrical Conductivity, Viscosity, and Aggregation Number Measurements

The binding of sodium dodecanoate (SDoD) to poly(ethylene oxide) (PEO) in aqueous solution was investigated and compared with the well-known polymer-surfactant complexes formed between PEO and sodium dodecyl sulfate (SDS). Electrical conductivity measurements indicated that the concentration ratio of bound SDoD to PEO (on monomer basis) was greater than that for the system PEO-SDS. However, the aggregation numbers of the micelles supported on the polymer chain are practically constant and similar for both surfactants at concentrations lower than the polymer saturation point. The difference in binding capability is explained in terms of a larger PEO coil expansion upon complexation of SDoD than in the case of SDS. An increase in the polymer surface favors the binding of SDoD to PEO in aqueous solution. This conclusion is supported by the results of the viscometric studies of PEO-surfactant solution.

Comparing Decyl-beta-maltoside and Octaethyleneglycol Mono n-Decyl Ether in Mixed Micelles with Dodecyl Benzenesulfonate

The interactions between polyvinylpyrrolidone (PVP) and a mixture of anionic and nonionic surfactants have been investigated by surface tension measurements. The surfactant mixtures are decyl-beta-maltoside (C(10)M) with dodecyl benzenesulfonate (C(12)BS) and octaethyleneglycol mono n-decyl ether (C(10)EO(8)) with C(12)BS. Surface tension measurements of the surfactant mixtures in the presence of PVP show that C(10)EO(8) competes more effectively than C(10)M with PVP in the interaction with C(12)BS. Copyright 2000 Academic Press.

Interactions between Quaternary Ammonium Surfactant Oligomers and Water-Soluble Modified Guars

The interaction between hydroxypropylguar (HPG) and its dodecyl-modified derivative (HMHPG) and cationic surfactant oligomers has been investigated by measurements of the solution viscosity at constant shear rate, microviscosity of the aggregates (dipyrenylpropane fluorescence emission spectra), and aggregation number of the polymer hydrophobe and of the surfactant (time-resolved fluorescence quenching). The surfactants are dodecyltrimethylammonium bromide (DTAB, monomeric surfactant) and some of its dimers and trimers which differed by the carbon number s of the polymethylene spacer connecting the surfactant moieties (2 </= s </= 20). Most results refer to a polymer concentration of 1 wt%. Only a weak interaction was evidenced between HPG and these surfactants, whereas strong interactions occurred between HMHPG and the surfactant oligomers. The interaction became stronger as the degree of oligomerization of the surfactant increased. The results led us to distinguish three ranges of concentration of added surfactant. The first range corresponds to surfactant concentrations below the surfactant cmc in water. In this range mixed aggregation occurs between polymer hydrophobes and surfactant ions, and the viscosity of the HMHPG + surfactant systems goes through a maximum, as usually found for associating polymers. The second range extends from the cmc to about 10 cmc. Precipitation of a polymer/surfactant complex occurs in this range with all surfactants forming threadlike micelles. For the other surfactants the viscosity goes through a minimum. In the third range, which corresponds to surfactant concentrations above 10 cmc, resolubilization of the precipitated HMHPG/surfactant complexes occurs and a solution-to-gel transition is observed for the surfactants which form threadlike micelles or vesicles. The concentration corresponding to this transition is about the same as that for pure surfactant solutions. Some polymer hydrophobes may contribute to the formation of additional bridges between surfactant micelles. Copyright 1999 Academic Press.

Ideal Mixing of Polymer-Surfactant Complexes of Polyethylene Oxide and Sodium Dodecyl Sulfate Plus Sodium Dodecanoate

Mixtures of the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecanoate (SDoD) were investigated regarding their ability to bind to a hydrophilic nonionic polymer, polyethylene oxide (PEO). By electrical conductivity measurements, the parameters with respect to the onsets of surfactant aggregation were determined in the presence of 0.06 M PEO (critical aggregation concentration) and in its absence (critical micelle concentration). It was found that both plots of these parameters for the multicomponent mixtures against molar fraction of SDoD showed an ideal mixing behavior. The same technique was used to estimate the degree of ionization as a fundamental parameter relating to the interfacial composition of mixed aggregates. In addition, in order to monitor changes in polymer-surfactant structures, we used steady-state quenching fluorescence measurements to characterize the sizes of PEO-SDS/SDoD complexes at different compositions of the complex mixture. Copyright 1999 Academic Press.