Influence of the Alkyl Chain Length of the Imidazole Ionic Liquid-Type Surfactants on Their Aggregation Behavior with Sodium Dodecyl Sulfate

et al. 2022

Langmuir

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The effect of the hydrocarbon chain length of ionic liquid surfactants 1-hexadecyl-3-alkyl imidazolium bromide [C16imC n ]Br (n = 1–16) on their aggregation behavior with polyoxyethylene lauryl ether (Brij 30) in aqueous solution was inspected. The rheological behavior, thermal properties, and microstructures of the different samples were studied using freeze-fractured electron microscopy. The interactions between [C16imC n ]Br and Brij 30 were studied using nuclear magnetic resonance spectroscopy and theoretical simulation. With the addition of Brij 30, the rodlike micelles of [C16imC n ]Br (n = 1, 2, 4, and 6) transition into wormlike micelles. The effects of the molar ratio of Brij 30 and [C16imC n ]Br and the hydrocarbon chain length of [C16imC n ]Br on the Brij 30/[C16imC n ]Br (n = 1, 2, 4, and 6) wormlike micelles were studied. When Brij 30 was mixed with the rodlike micelles of [C16imC8]Br, the Brij 30/[C16imC8]Br mixtures form wormlike micelles at low Brij 30 concentration and gels at high Brij 30 concentration. The [C16imC n ]Br (n = 10, 12, 14, and 16) rodlike micelles were induced by Brij 30 to turn into the Brij 30/[C16imC n ]Br gels. The effect of the [C16imC n ]Br hydrocarbon chain length on their rodlike micelles with the addition of Brij 30 is also theoretically discussed.

Section: Introductionmentioning

confidence: 99%

Brij 30 Induced Transition of Rodlike Micelles to Wormlike Micelles and Gels in the Imidazole Ionic Liquid Surfactants: The Alkyl Chain Length Effect

Chen

et al. 2022

Langmuir

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“…Thus, τ R decreases exponentially with increasing temperature because surfactant monomers jump more rapidly between the cylindrical body and hemispherical end caps of the wormlike micelles at higher temperatures . When the temperature reaches 80.0 °C, G ″ is always larger than G ′, indicating the existence of rodlike micelles . So the wormlike micelles convert to rodlike micelles at higher temperatures.…”

Section: Resultsmentioning

confidence: 96%

Unusual Increasing Viscoelasticity of Wormlike Micelles Composed of Imidazolium Gemini Surfactants with Temperature

Chen

et al. 2023

Langmuir

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The viscoelasticity of wormlike micelles composed of ionic surfactants typically shows an exponential decrease with increasing temperature, which limits their application in relatively high-temperature (>90.0 °C) oilfields and the synthesis of functional materials as supramolecular templates at high temperatures. In this work, a series of imidazolium gemini surfactants, 1,9-(ethane-1,2-diyl)bis(3-alkyl-1H-imidazol-3-ium) bromide ([C n -2-C n im]Br2, n = 12, 14, 16, 18, 20), were synthesized. Their surface activities and aggregation behaviors in water were studied by electrical conductivity, rheology, polarization optical microscopy, small-angle X-ray scattering, ζ potential, and hydrogen nuclear magnetic resonance measurements. [C12-2-C12im]Br2 and [C14-2-C14im]Br2 mainly precipitate in water. [C n -2-C n im]Br2 (n = 16, 18, 20) forms lamellar liquid crystals over a large range of concentrations at low temperatures. With the increase of temperature, the lamellar liquid crystals transit to wormlike micelles. Interestingly, the viscoelasticity of the three wormlike micelles first increases to the maximum and then decreases with increasing temperature. These wormlike micelles without additives retain high viscoelasticity up to 90.0 °C or above. With the increase of the alkyl chain length of the surfactants, the transition temperature of lamellar liquid crystal to wormlike micelles and the disintegration temperature of wormlike micelles increase. The unusual increase of the viscoelasticity of wormlike micelles was due to the desorption of weakly bound counterions and the extension of the long hydrophobic chains of surfactants at high temperatures.

“…The advantage of the cryogenic transmission electron microscopy (cryo-TEM) is that it can directly image the morphology and microstructure of soft materials in solution. , The cryo-TEM was employed to directly image the structures and morphologies of the aggregates in the 95.0 mM [C 18 imC 9 ]Br/NaSal wormlike micelles. As shown in Figure , the cross-linked stereo-specific multistage network consists of long and flexible entangled micelles.…”

Section: Resultsmentioning

confidence: 99%

Effect of Sodium Salicylate on Improving the Lubricating Properties of [C₁₈imC₉]Br Wormlike Micelles in Glycerol/Propylene Glycol at Low Temperatures

Sun²,

ACS Sustainable Chem. Eng.

et al. 2022

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The formation of long cylindrical wormlike micelles at low temperatures (near 0 °C) is relatively rare. In this work, the effect of different salts on the viscoelasticity of the formed wormlike micelles by the ionic liquid surfactant (1-octadecyl-3-nonyl imidazolium bromide, [C18imC9]Br) and glycerol/1,2-propanediol mixture at low temperature was studied. The rheological measurements revealed that only sodium salicylate (NaSal) can increase the viscoelasticity of [C18imC9]Br wormlike micelles by up to 15 times and the existence of temperature range. When the [C18imC9]Br concentration is fixed, the viscoelasticity of the [C18imC9]Br/NaSal wormlike micelles increases and then decreases with the increase of NaSal concentration. Tribological results show that the [C18imC9]Br/NaSal wormlike micelles have excellent friction reduction and antiwear properties for steel/steel contact at 6.00 °C. The friction coefficient and wear volume of [C18imC9]Br/NaSal wormlike micelles first decrease and then increase with the increase of the NaSal concentration. In addition, their tribological properties are significantly better than those of pure [C18imC9]Br wormlike micelles under the same conditions. The lubrication effect of [C18imC9]Br/NaSal wormlike micelles at low temperatures is improved due to the adhesion of [C18imC9]Br/NaSal wormlike micelles and the protective film formed by the tribochemical reaction.