Titration microcalorimetry of adsorption processes in aqueous systems Interaction of sodium dodecylsulfate and sodium decylsulfate with poly(N-vinylpyrrolidone)

Abstract

Procedures are described for analysing enthalpograms characterising adsorption by macromolecules in solution recorded using a titration microcalorimeter. The experimental procedure involves injecting small aliquots of a solution containing adsorbate into a sample cell containing a solution of macromolecular adsorbent. Treatments based on both Langmuir and Frumkin adsorption isotherms are described. The procedures are illustrated by application of the derived equations to the interaction of micelles of sodium dodecylsulfate(aq) and of sodium decylsulfate(aq) with the water-soluble polymer, PVP. The dominant features in the recorded enthalpograms are described using equations developed from the Frumkin equation. In both cases the adsorption is endothermic attributed to hydrophobic interactions between polymer and surfactant. However, an important feature of the analysis is the characterisation of adsorbateÈadsorbate interactions using enthalpic interaction parameters. The enthalpograms are characterised by three composition ranges : (i) micelle deaggregation and weak interaction of monomers with polymer, (ii) micelle adsorption on to the soluble polymer up to surface saturation and (iii) micelle dilution.

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

“…The bulk experimental property is determined as a function of internal parameters and treated by means of proper theoretical approaches to obtain information at molecular level. Such a technique was successful in describing, from a quantitative viewpoint, cyclodextrin þ surfactant, 28,29 homopolymer þ surfactant 30,31 and copolymer þ surfactant [32][33][34][35] aqueous systems. The adsorption of conventional surfactants onto a solid substrate is generally studied through the ITC method.…”

“…[36][37][38] However, the titration curves are combined with the isotherms of adsorption, determined from independent experiments, to obtain the enthalpy for the adsorption process. [36][37][38] To our knowledge, only Blandamer et al 31 used the Frumkin adsorption isotherm for analyzing titration microcalorimetry data of aqueous surfactant-polymer systems.…”

Encapsulation Processes by Bilayer Vesicles

“…Titration microcalorimetry yields binding constants and, when applied as a function of temperature, full thermodynamic details for the binding process. 65 DSC provides details about the disturbance of the bilayer system by the solubilized guest from which conclusions may be drawn about the preferred binding locations.…”

23Na relaxation in SDS and SDES–polymer systems

“…At the same time, they are very interesting also from the fundamental point of view because of the concurrence of both electrostatic interactions [1] and hydrophobic forces, responsible for the micellization phenomenon [2], and of the relevant role played by cooperativity [3].…”