Ultralong-Chain Ionic Liquid Surfactants Derived from Natural Erucic Acid

Abstract

Ionic liquid surfactants (ILSs) have shown increasing promise for substituting the traditional amphiphiles because of their flexible tunability and advantageous physicochemical properties. However, the improvement of common ILSs in terms of self-assembly ability and thickening ability remains a significant challenge. Herein, two novel ultralong-chain ILSs (ULILSs), ErBCho (choline cis-4-erucylamidobenzoate) and ErBBTA (benzyltrimethylammonium cis-4-erucylamidobenzoate), were designed and synthesized from natural unsaturated fatty acid (erucic acid). Their structures were characterized via 1H NMR, 13C NMR, and electrospray ionization-mass spectrometry techniques, and physicochemical properties were evaluated by surface tension, polarized optical microscopy, and rheology. The insertion of a phenyl ring between the charged headgroup and unsaturated C22-tail significantly enhanced the hydrophobicity of ULILSs, but they retained the desirable characteristics of ILSs (low melting temperature) and excellent water-solubility (Krafft temperature <4 °C), for application in low-temperature water. Compared with counterparts without a phenyl ring, the critical micelle concentration (cmc) of the presented ULILSs was markedly decreased by at least an order of magnitude (particularly cmc of ErBBTA 3.5 μM), and interfacial activity was higher (larger pC 20). In particular, the current ULILSs were able to form wormlike micelles on their own and then thicken the solution at relatively low overlapping concentrations (1.68–5.71 mM), without any additives and regardless of counterions. More importantly, viscoelastic fluids formed by the current ULILSs (especially ErBBTA) were not only resistant to high temperature and cycled shear but also exhibited excellent sand-carrying and oil-induced gel-breaking performances. Such ULILSs have shown promise to replace those common surfactants in hydro-fracturing and other applications.

Alkane-Strengthened Viscoelasticity in Micellar Solutions of Surface-Active Ionic Liquids and Their Potential Application in Enhanced Oil Recovery

“…The presence of a WLM network is indicated when the transition of the increasing trend shifts from linear to exponential. The breakpoint is often termed the critical overlapping concentration (C*), which was calculated to be 4.43 wt % …”

“…The lower melting point of BD-OA could be attributed to the significant volumetric asymmetry between the fatty acid anions and quaternary ammonium counterions, which prevent the formation of strong electrostatic interactions and tight crystal packing. 41 Additionally, TGA experiments demonstrated the onset of decomposition of BD-OA at 290.5 °C (Figure S3), indicating its remarkable thermal stability. The results from DSC and TGA results both revealed that BD-OA falls within the category of ILSs.…”

“…The breakpoint is often termed the critical overlapping concentration (C*), which was calculated to be 4.43 wt %. 41 Figure 3c exhibits the dynamic frequency sweep for BD-OA solutions with concentrations ranging from 6% to 10%. Within this range, elastic modulus (G′) exceeds the viscous modulus (G″) at high frequencies and falls below G″ at low frequencies, which is typically considered a key proof of WLMs.…”

Rheology and delayed micellar formation process of novel tetrameric cationic surfactant fracturing fluid

“…Good proppant‐carrying capacity of fracturing fluids is required to possess sufficient strength to deliver proppant evenly into the fractures (Hari et al, 2021). If the proppant‐suspending capacity of fracturing fluid is poor, proppants will drop rapidly and cannot be transported into the deep fractures of reservoirs, so it is significant to carry out the proppant‐suspending test (Zhang et al, 2022).…”

Review on High-Temperature-Resistant Viscoelastic Surfactant Fracturing Fluids: State-of-the-Art and Perspectives

“…The temperature resistance of the formed blending surfactant systems can reach 160 °C, but no other fracturing fluid performance test data was provided. Zhang et al 268 found that using benzyltrimethylammonium cation instead of choline cation can further reduce the cmc of the erucic-based VES fluids and improve the temperature resistance. Due to the insertion of phenyl into the hydrophobic region formed by the erucic acid tails, the arrangement among surfactants is more compact.…”