Zhiyu Huang

pH-responsive anionic wormlike micelle based on sodium oleate induced by NaCl.

A pH-responsive anionic surfactant wormlike micellar system induced by NaCl has been developed. In this work, the anionic surfactant, sodium oleate (NaOA) solutions, transforms from low-viscosity fluid into high-viscoelastic solution induced by NaCl of 200 mM to 350 mM concentration. According to the above, the solution reversibility has been studied via changing pH value of the solution. This pH-responsive solution can be promptly switched between gel-like solution and waterlike fluid in a narrow pH value range. Steady and dynamic rheological measurements are employed to characterize the pH-responsiveness at different pH. The transformation between wormlike micelle and spherical micelle in the various pH solutions is demonstrated by dynamic light scattering tests, cryo-TEM, and NMR measurements. The pH-responsive property of the system is attributed to the carboxylate ion contained by sodium oleate. With higher pH value, the ionized carboxylate combines with NaCl closely and thus forms wormlike micelles. On the contrary, sodium oleate converts to oleate acid when pH decreases. In this way, spherical micelles are transformed because of the weaker interaction between oleate aicd and NaCl.

Ionic liquid capped carbon dots as a high-performance friction-reducing and antiwear additive for poly(ethylene glycol)

Ionic liquid (1-aminopropyl-3-methyl-imidazolium bromide) capped carbon dots (CDs-Br), with a mean particle size of 1.73 nm and poor crystallinity, have been successfully synthesized by a one-pot pyrolysis method. The CDs-NTf2 were obtained from the CDs-Br by an anion exchange reaction between Br− and N(CF3SO2)2− (NTf2−). The NTf2− endowed the CDs-NTf2 with wonderful dispersion stability in poly(ethylene glycol) (PEG). The tribological performances of CDs-NTf2 as the lubricant additive for PEG were investigated in detail using a four-ball model by altering the concentration of CDs-NTf2, the test load and the duration. The results demonstrated that these CD-NTf2-based additives exhibited excellent friction-reducing and antiwear properties. In particular, the friction coefficient and wear scar diameter (WSD) of lower balls lubricated by PEG under 392 N correspondingly reduced by 70% and 33% when 0.3 wt% of CDs-NTf2 was introduced. The WSD reduction further increased by 45% when the test load was increased to 600 N. Moreover, the CD-NTf2-based additives could work for a long time without weakening the lubrication capabilities. The lubricating mechanism of CD-NTf2-based additives has also been proposed and illustrated that the synergistic lubricating effect of CDs-NTf2, including film lubrication of IL groups and nano-lubrication of carbon cores such as rolling, mending and polishing effects, might account for their outstanding tribological behaviors. The above results indicate that CDs are expected to be utilized as a kind of designable and high-performance lubricant additive and find wide applications in machinery and equipment.

Solution and Adsorption Properties of Hydrophobically Associating Polyacrylamide Prepared in Inverse Microemulsion Polymerization

The hydrophobically associative polyacrylamide (HAPAM) with homogeneous composition was prepared in inverse microemulsion polymerization. The homogeneity was proved by polymerization kinetic. The critical association concentration (CAC) was measure by three methods: viscosity method, fluorescence method and micro-pore method. The results showed that the HAPAM still could exhibit hydrophobic association interaction in porous media under flowing condition. HAPAM could present adsorption of multi-layer due to the hydrophobic association interaction. Its the hydrophobic association interaction that made the adsorption behavior differ from neutral PAM.

Synthesis and corrosion inhibition performance of alkyl triazole derivatives

Green corrosion inhibitor, maleic acid mono-(1-alkyl-1H-[1, 2, 3]-triazol-4-ylmethyl) ester (Mal-Tr-R) with three different lengths of carbon chain were synthesized by nucleophilic substitution reaction, click coupling reaction, and esterification reaction. The final products were characterized by elemental analysis, FT-IR and 1H NMR spectra, indicating that the products were successfully synthesized. The corrosion inhibition efficiencies of Mal-Tr-R in hydrochloric acid solution were evaluated by weight loss and electrochemical methods. The adsorption equilibrium constant (K0) and standard thermodynamic parameters of adsorption were calculated. The surface microstructure of the mild steel was studied through scanning electron microscope. The results indicated that the Mal-Tr-R can act as effective corrosion inhibitors in hydrochloric acid solution for mild steel. It was also determined that the inhibition efficiency of Mal-Tr-R increases with the increase of the carbon chain at low temperature, but the opposite trend appears at high temperature.

Retention Behaviors of Hydrophobically Associating Polyacrylamide Prepared via Inverse Microemulsion Polymerization Through Porous Media

The retention behavior of hydrophobically associative polyacrylamide (HAPAM) with homogeneous composition in porous media was investigated. The results showed that HAPAM could exhibit different retention behavior, compared to PAM due to the existence of hydrophobic association group in HAPAM molecular frame. The critical association concentration could also be reflected by the curves between HAPAM concentration and retention amount. The retention amount of HAPAM was higher than that of polyacrylamide (PAM) and was smaller than the absorption amount of HAPAM. The retention mechanism was mainly controlled by adsorption mechanism.

Application of CO2-Triggered Switchable Surfactants to Form Emulsion with Xinjiang Heavy Oil

Owing to the high acid number of Xinjiang heavy oil and incomplete demulsification after pipelining, this article discusses the application of CO2-triggered switchable surfactants to the emulsified transport of several Xinjiang heavy oils in the pipeline. Results show that CO2-triggered switchable surfactants promote the formation and stabilization of oil-in-water (O/W) emulsion in the absence of CO2 as a base. The property parameters of heavy oils fundamentally influence the indigenous emulsifying agents. The emulsion is stable when the heavy oil has a high acid number and low asphaltene content, which is also affected by some physical factors.

Copolymer SJ-1 as a Fluid Loss Additive for Drilling Fluid with High Content of Salt and Calcium

A ternary copolymer of 2-acrylamide-2-methyl propane sulfonic acid (AMPS), acrylamide (AM), and allyl alcohol polyoxyethylene ether (APEG) with a side chain polyoxyethylene ether SJ-1 were designed and synthesized in this work. Good temperature resistance and salt tolerance of “” of AMPS, strong absorption ability of “amino-group” of AM, and good hydrability of side chain polyoxyethylene ether of APEG provide SJ-1 excellent properties as a fluid loss additive. The chemical structure of ternary copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The molecular weight and its distribution were determined by gel permeation chromatography (GPC). The API fluid loss of drilling fluid decreased gradually with the increasing concentration of NaCl and CaCl2 in the mud system. SJ-1 was applied well in the drilling fluid even at a high temperature of 220°C. Results of zeta potential of modified drilling fluid showed the dispersion stability of drilling fluid system. Scanning electron microscopy (SEM) analysis showed the microstructure of the surface of the filter cake obtained from the drilling fluid modified by SJ-1.

CO2-/N2-Triggered Viscoelastic Fluid with N,N-Dimethyl Oleoaminde-Propylamine and Sodium p-Toluenesulfonate

In this article, a new type of CO2-triggered switchable wormlike micelles based on N,N-dimethyl oleoaminde-propylamine (DOAPA) and sodium p-toluene sulfonate (SPTS) mixed in a molar ratio of 1:1 is studied. With inlet of CO2, DOAPA molecules are protonated to form quaternary ammonium. The electrostatic attraction between quaternary ammonium and SPTS results in assembled structures and formation of a viscoelastic wormlike fluid. These results are proved by rheological methods in this study. Upon the release of CO2, the quaternary ammonium is deprotonated back to tertiary amines, the assemble structures are split, and water-like fluid is obtained. Such a reversible transition of viscosity between high and low can be repeated several times with or without CO2. This transition of the micromolecular structure is proved by 1H NMR and conductivity. As well, the process of viscosity reduction can be controlled by the flow rate of N2 addition.

Synthesis and Properties of a Series of CO2 Switchable Gemini Imidazolium Surfactants

Abstract Novel switchable gemini imidazolium surfactants with different carbon atoms in hydrophobic group were successfully synthesized by condensation of fatty acid with triethylene tetramine, then the intermediates were reacted with CO2 to give the imidazolinium bicarbonates. The structures of intermediates and products were identified by IR and 1H-NMR spectra. As the results show, the structures of the products obtained correspond to the target compounds designed. By surface tension measurements, these Gemini surfactants have excellent surface activity with low cmc and surface tension. The conductivity and surface tension cycles show that these surfactants could be switched from imidazoline (neutral form) to imidazolium bicarbonate (charged form) reversibly and repeatedly.

Foaming Properties of CO2-Triggered Surfactants for Switchable Foam Control

Switchable surfactants, particularly those triggered by CO2 used for switchable foam control, are relatively less documented. In this article, the foaming performance of 2-alkyl-1-hydroxyethylimidazolinium bicarbonate cationic surfactants (HEAIBs) was investigated for the first time. The foaming properties of these surfactants demonstrate that HEAIBs can generate foam with moderate stability, on demand, can be rapidly yet reversibly dissipated upon exposure to air. The results illustrated such a facile trigger, and the foam on/off transition would have huge potential to form a new class of stimuli-response foaming agents.