Correlations between temperature-dependent rheology and electrostatic interactions in reverse wormlike micelles induced by inorganic salts. Issue 14 (26th March 2020)

• Record Type: Journal Article
• Authors: Chang, Hung-Ming; Lin, Chia-Yi; Tung, Shih-Huang
• Is Part Of: Soft matter. Volume 16:Issue 14(2020)
• Page Start: 3505
• Page End: 3513
• Publication Date: 2020-03-26
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c9sm02508a
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Temperature-dependent rheological properties are correlated with the strength of the electrostatic interaction that drives the formation of reverse wormlike micelles. Abstract : Previous studies have shown that the plateau modulus G p of the wormlike micelles formed in water driven by hydrophobic interactions is a constant upon heating, similar to polymer solutions, and G p of the reverse worms formed in oils driven by hydrogen bonding decreases with increasing temperature. In this work, we investigated the reverse worms induced by three chloride salts that bind lecithin through different strengths of electrostatic interactions, in the order of LaCl3 > CaCl2 > LiCl. We correlated the interaction strengths with the temperature-dependent rheological properties and found that upon heating, G p for all the reverse worms driven by electrostatic interactions decays slower than that driven by the weak temperature-sensitive hydrogen bonding. Furthermore, the decay rates of G p follow an order in the inverse relation to the interaction strength, LaCl3 ≤ CaCl2 < LiCl, indicating that the dependence of G p on temperature can reflect the strength of the driving forces for micellization. We utilized Fourier transform infrared spectroscopy (FTIR) to confirm the weakening of the interaction and the small angle X-ray scattering (SAXS) technique to reveal the decrease in the lengths of the reverse worms as temperature increases, both of which echo the changes in the rheological properties.