Thermodynamic Study of the Micellization of Zwitterionic Surfactants and Their Interaction with Polymers in Water by Isothermal Titration Calorimetry

Abstract

The micellization of a homologous series of zwitterionic surfactants, a group of sulfobetaines, was studied using isothermal titration calorimetry (ITC) in the temperature range from 15 to 65 °C. The increase in both temperature and the alkyl chain length leads to more negative values of ΔGmic(0) , favoring the micellization. The entropic term (ΔSmic(0)) is predominant at lower temperatures, and above ca. 55-65 °C, the enthalpic term (ΔHmic(0)) becomes prevalent, figuring a jointly driven process as the temperature increases. The interaction of these sulfobetaines with different polymers was also studied by ITC. Among the polymers studied, only two induced the formation of micellar aggregates at lower surfactant concentration: poly(acrylic acid), PAA, probably due to the formation of hydrogen bonds between the carboxylic group of the polymer and the sulfonate group of the surfactant, and poly(sodium 4-styrenesulfonate), PSS, probably due to the incorporation of the hydrophobic styrene group into the micelles. The prevalence of the hydrophobic and not the electrostatic contributions to the interaction between sulfobetaine and PSS was confirmed by an increased interaction enthalpy in the presence of electrolytes (NaCl) and by the observation of a significant temperature dependence, the latter consistent with the proposed removal of hydrophobic groups from water.

Nanoparticle induced formation of self-assembled zwitterionic surfactant microdomains which mimic microemulsions for the in situ fabrication and dispersion of silver nanoparticles

“…The CMCs of a homologous series of zwitterionic surfactants in water are temperature dependent; namely, as the temperature is increased, an initial slight decrease in the CMC value is observed until a minimum value is reached aer which the CMCs start to increase with temperature. [28][29][30] The CMC of C 10 -APSO 4 increased with temperature (i.e. 0.24 w/w%, 0.38 w/w%, and 0.44w/w% for 25 C, 35 C, and 42 C, respectively; Fig.…”

Properties and applications of amphoteric surfactant: A concise review

“…With an increase in temperature, the values of Δ mic G o become more negative, which encourages micelle development. The micellization mechanism is endothermic at low temperatures (Brinatti et al, 2014). The micellization mechanism becomes exothermic as the temperature increases.…”

Applications of isothermal titration calorimetry - the research and technical developments from 2011 to 2015

“…This number of papers is impractical to cite in full so the author has selected approximately 200 that he feels best represents the field and apologizes for any resulting omissions. These references have been classified into the following broad categories: references cited in the introduction, review and perspective articles, methods papers, protein : protein interactions, protein interactions with other ligands, lipids, micelles and membranes, polysaccharides, nucleic acids, synthetic chemicals, polymers and nanoparticles,…”