Hydrodynamic and thermodynamic aspects of the SDS-EHEC-water system

Abstract

The specific interaction between a strongly hydrophobic but still water-soluble cellulose derivative, ethyl(hydroxyethy1)cellulose (EHEC), and a low molecular weight anionic surfactant, sodium dodecyl sulfate (SDS), is studied in dilute solution without added neutral electrolyte by means of hydrodynamic (viscosity) and thermodynamic (dialysis equilibrium) measurements. The dialysis equilibrium shows strong adsorption of SDS at concentrations far below the normal cmc for SDS. The dialysis equilibrium is sensitive to the polymer concentration at higher SDS concentrations where the adsorption seems to decrease. In the region of increasing adsorption of SDS to EHEC the hydrodynamic measurements reveal a drastic reconformation of the polymer in dilute solution leading to a 4-fold reduction in hydrodynamic volume. At higher polymer concentrations the viscosity passes through a very marked maximum when the SDS concentration is increased. The results are interpreted in terms of a clustering theory for the SDS adsorption.

Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

“…34 In addition, the maximum viscosity at 4 × 10 -3 mol L -1 is also close to the value observed for SDS/ethyl(hydroxyethyl)cellulose systems independently of the polymer concentration. 1,14,35 The occurrence of the maximum viscosity above C 1 can be attributed to the formation of interchain polymersurfactant complexes. 1,3,36 The subsequent decrease in the viscosity with increasing SDS concentration indicates that the aggregate formation leads to a more compact polymer structure due to intrachain polymer-surfactant complexes.…”

The Interaction between Hexadecyltrimethylammonium Bromide to Poly (Ethylene Glycol) with Different Molecular Weights and Some Schiff-Bases Investigated by Surfactant Ion Selective Electrode

“…We believe that the clue to the explanation for this unusual result is analogous to that proposed earlier by Holmberg et al to explain the primary step in the formation of polymer/surfactant complexes. 19 In the present systems the bound surfactant in the T 1 -T f region polymer and schiff-base are a "loose" aggregate which only binds a small amount of Br − counter ion. However the positive charge density at the surface of these bound aggregates are likely to attract Br − counter ions in such a way that the local concentration of Br − ions in the microenvironment of the complex is much higher than their bulk concentration.…”

“…Unfortunately we have not been able to observe any point at which the EMF data merge after binding in the present work and also in previous electrode studies on cationic surfactants. 14,19 We believe that part of this problem may be due to the electrode not responding ideally at higher surfactant concentrations. Certainly we have found that the high surfactant concentration response of the electrode is dependent on the origin of the modified poly vinyl chloride used for the membrane and also on high salt concentration.…”

Polymer-Amphiphile Interactions: An Overview

“…These are very helpful for the specific targeting to tissues or cells. Synthetic polymers are utilized to get a broad and united picture of the interaction as this show a discrepancy in the nature and degree of substitution [35].…”