Determination of binding isotherms of ionic surfactants in polymer gels

Abstract

A thermodynamic analysis of the equilibrium of ionic surfactant solutions with polymer solutions, polymer microgels and macrogels is given. It is concluded that the amount of surfactant bound to the polymer cannot be calculated exactly from the total and equilibrium surfactant concentration measure-ments. A trace probe electrolyte method is suggested for the determination of the binding isotherm of the surfactant.

Effect of surfactant concentration on the responsiveness of a thermoresponsive copolymer/surfactant mixture with potential application on “Smart” foams formulations

“…Equation ( 6) is valid if a c f is smaller than the cmc and if either the ionic strength of the solution is high, or the charge density and the polymer concentration is not too high. [54,60].…”

Competitive adsorption of sodium dodecyl sulfate and polyethylene oxide at the air/water interface

“…Finally, the term c mic accounts for the surfactants in micelles. Equation (10) can be simplified because the NaBr is in a large excess in which case the e y factor is practically equal to one [37,38]. Moreover, the present discussion is restricted to values of c SDS below the range of occurrence of free micelles of the surfactant [12] therefore c mic = 0.…”

“…The factor e y is a correction term which accounts for the interaction between the free surfactant ions and the charged polymer/surfactant aggregates [37,38]. The variable B is the amount of surfactant bound to the polymer.…”

“…In the presence of charged surfactant aggregates the following expression for the total SDS concentration was derived from the exact mass balance of the system [37,38]: (10) c SDS = c e,SDS e y + Bc PEO + c mic .…”

Transmission behavior of pNIPAM microgel particles through porous membranes

“…Currently, post-synthesis purification of microgels is generally carried out by repeated dialysis against fresh water [6]. Although dialysis gives acceptable purity for product development grade material, it is a diffusion-driven, equilibriumlimited process and so small amounts of impurities could be left behind [7][8][9]. This raises doubts as to whether clinical-grade microgel could indeed be produced by dialysis.…”