Microcalorimetry Study of Interaction between Ionic Surfactants and Hydrophobically Modified Polymers in Aqueous Solutions

Abstract

The interactions of hydrophobically modified poly(acrylamide) (HMPAM) and unmodified poly(acrylamide) (PAM) with sodium dodecyl sulfate (SDS) or tetradecyltrimethylammonium bromide (TTAB) have been studied by flow microcalorimetry at 302.7 K. The mixing enthalpy curves were determined by mixing SDS and TTAB solutions above their critical micelle concentration with HMPAM or PAM solutions of different concentrations. The mixing enthalpy curves of SDS and TTAB solutions with water were also determined. The critical aggregation concentrations (cac) and the thermodynamic parameters have been derived from the differential enthalpy curves. Pronounced endothermic peaks were detected for all the systems. The peak heights of the endothermic curves decrease with increasing hydrophobicity of the HMPAM samples. The HMPAM hydrophobicity has no obvious effect on the values of the cac. The interaction between TTAB and the polymers is much weaker than that between SDS and the polymers.

Physicochemical Investigations on the Interaction of Surfactants and Salts with Polyvinylpyrrolidone in Aqueous Medium

“…We have also not observed changes in CMC for CTAB and TTAB in PVP solution but have observed a change in the enthalpy of micellization, H o m . Wang et al (16) have observed that TTAB does undergo interaction with PAA (mol wt ∼200,000) as indicated by changes in both the CAC and the CMC, but the strength of binding is lower than that of SDS.…”

“…The hydrophobic interaction between the micelle and the polymer is thus reduced; for a favorable interaction, the polymer must be hydrophobically modified. Using microcalorimetric measurements, Wang et al (16) have very recently reported that both hydrophobically unmodified and modified PAA can interact with both SDS and TTAB as indicated by both the CAC and the CMC, but the interaction with SDS is stronger than that with TTAB. A good reason for the interaction observed by Wang et al for TTAB could be that it is more hydrophobic than DTAB.…”

“…As well, microcalorimetry has been successfully used in recent years to derive thermodynamic information on surfactant interactions with macromolecules including hydrophobically modified neutral polymers (5,(15)(16)(17).…”

Interaction of Ionic Species and Fine Solids with a Low Energy Hydrophobic Surface from Contact Angle Measurement

“…This orientation is dictated by the competition of hydrophobic interaction with electrostatic interaction between the surfactant and the substrate, and is influenced by the structure of both the surfactant and the substrate, as well as the degree of hydrophobicity of the substrate (37,38). For a strongly hydrophobic surface, it is usually accepted that the hydrocarbon chain of surfactant faces the surface, leaving the polar group exposed to water, and thus causing a reduction in contact angle.…”

Polymer-Amphiphile Interactions: An Overview

“…There are also reports of the free micelle formation long before the polymer saturation [29,30]. Usually, the cac does not depend on molecular weight of polymer, it depends on the nature of polymer and the polymer saturation concentration [30,31]. The amphiphile-polymer interactions have many applications in various areas, but in the field of colloid chemistry it has become more important in view of their extensive industrial applications [32].…”