Thermo-responsive gels based on supramolecular assembly of an amidoamine and citric acid

Abstract

In this work, we report the formation of a novel, aqueous-based thermo-responsive, supramolecular gelling system prepared by a convenient and efficient self-assembly of a long-chain amino-amide and citric acid. To determine the viscosity behavior and to gain insights into the gelation mechanism, a complementary combination of techniques, including Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and sinusoidal oscillatory tests, were used. The supramolecular gelator exhibited remarkably reversible sol-gel transitions induced by temperature at 76 °C. At a concentration of 5 wt%, the zero-frequency viscosity of the supramolecular system increased by about four orders of magnitude (from 4.2 to 12 563 Pa s) by changing the temperature from 23 °C to 76 °C. The viscous nature of the supramolecular gel could be preserved up to 90 °C. The synergistic combination of the hydrogen bonding between amino and carboxylic acid groups and the electrostatic interactions arising from the protonation of the amino-group and the deprotonation of carboxylic acid groups enhanced at higher temperatures is presumably responsible for the thermo-responsive behavior. We anticipate that these supramolecular gelators can be beneficial in various applications such as hydrogel scaffolds for regenerative medicine, personal care products and cosmetics, and enhanced oil recovery as viscosity modifiers.

Natural Berberine-Based Chinese Herb Medicine Assembled Nanostructures with Modified Antibacterial Application

“…This might be due to the electrostatic interaction between the carboxyl group and quaternary ammonium ion. The electrostatic interaction led to weak bond strength and slowed down the stretching vibration frequency of the CO double bond. , This was accordant with the further 1D/2D NMR assay.…”

“…The electrostatic interaction led to weak bond strength and slowed down the stretching vibration frequency of the CO double bond. 35,36 This was accordant with the further 1D/2D NMR assay. Furthermore, the fluorescence characteristics of selfassemblies were investigated by fluorescent spectrophotometry.…”

Phenoxy‐Alkyl Maleates as Phase‐Selective Organogelators for Gelation of Edible Oils

“…In general, the gels self‐assembled network structures are formed due to non‐covalent attractions such as π–π stacking, van der Waals, hydrogen‐bonding, electrostatic interactions, and solvophobic effects . These non‐covalent interactions depend on the molecular geometry of the gelator molecule and decide the affinity toward the gelation of the specific liquid mediums.…”

pH-responsive viscoelastic supramolecular viscosifiers based on dynamic complexation of zwitterionic octadecylamidopropyl betaine and triamine for hydraulic fracturing applications

“…The reaction of chloroacetic acid with amino–amide resulted in the emergence of a shoulder at 3380 cm −1 which is likely to be because of the O–H stretching from carboxylic terminal group of OAPB. 47,48 Overall, when we put these pieces together, we can conclude the successful synthesis of OAPB as illustrated in Fig. 1 .…”