Search Results (99)

The petroleum industry faces intensifying challenges related to the depletion of easily accessible reservoirs and the growing energy demand, necessitating the adoption of advanced chemical agents that can operate under extreme conditions. Cationic gemini surfactants, characterized by their unique dimeric architecture consisting of two hydrophilic head groups and two hydrophobic tails, have emerged as superior alternatives to conventional monomeric surfactants due to their enhanced interfacial activity and physicochemical resilience. This review provides a comprehensive analysis of the literature concerning the molecular structure, synthesis, and functional applications of cationic gemini surfactants across the entire oil value chain, from extraction to refining. The analysis reveals that gemini surfactants exhibit critical micelle concentrations significantly lower than their monomeric analogs and maintain stability in high-temperature and high-salinity environments. They demonstrate exceptional efficacy in enhanced oil recovery through ultra-low interfacial tension reduction and wettability alteration, while simultaneously serving as effective drag reducers, wax inhibitors, and dual-action biocidal corrosion inhibitors in transportation pipelines. Cationic gemini surfactants represent a transformative class of multifunctional materials for the oil industry. Full article

Cationic gemini surfactants, which constitute a unique class of amphiphilic molecules composed of two hydrophilic ammonium groups and two hydrocarbon tails connected by a spacer, have emerged as highly versatile functional agents with superior interfacial activity and self-assembly behavior compared to conventional monomeric analogs. Their structural tunability enables precise control over physicochemical properties, making them attractive for applications across diverse scientific and industrial domains. In biomedical sciences, gemini surfactants act as potent antimicrobial and anti-biofilm agents, as well as efficient carriers for drug and gene delivery. In nanotechnology and optoelectronics, they facilitate the synthesis and stabilization of nanoparticles, quantum dots, and perovskite nanocrystals, leading to improved colloidal stability, enhanced photophysical performance, and extended material lifetimes. Within the petroleum industry, gemini surfactants have proven effective in enhanced oil recovery (EOR) by reducing interfacial tension and in crude oil transportation as drag-reducing agents (DRAs), significantly lowering viscosity, turbulence, and pipeline energy losses. This review summarizes recent advances in the chemistry, mechanisms of action, and applications of gemini surfactants, highlighting their multifunctionality and emphasizing their potential in the development of next-generation sustainable technologies. Full article

Addressing the issues of low permeability, stress sensitivity in CBM reservoirs, and severe reservoir damage from traditional fracturing fluids, we prepared a Gemini surfactant (designated GEM-CBM) for CBM development using ethanolamine, epichlorohydrin, and alkylamidopropyl dimethylamine as feedstocks. On this basis, we further developed a clean fracturing fluid system. The synthesis process of GEM-CBM was optimized via single-factor and orthogonal experiments. The surface activity of GEM-CBM was assessed through surface tension measurements, whereas the sand-carrying capacity, the rheological properties, gel-breaking performance, and reservoir compatibility were comprehensively examined. The optimal conditions for GEM-CBM are listed as follows: the molar ratio of intermediate to alkylamidopropyl dimethylamine being 1:2.2, reacted at 80 °C for 20 h, with a conversion rate of 96.5%. FTIR verified the existence of characteristic functional groups, and EA results matched the theoretical molecular composition. GEM-CBM has good performance, with a critical micelle concentration (CMC) of 19.0 μmol/L and a surface tension at CMC (γCMC) of 37.44 mN/m. The optimized clean fracturing fluid (formulation: 2.3% GEM-CBM + 0.3% Tween-80 + simulated formation water with 150,000 mg/L mineralization) exhibited a viscosity of 82 mPa·s (66.7% viscosity retention rate) after being subjected to 100 min of shearing at 90 °C and 170 s⁻¹. At 90 °C, the proppant settlement velocity was less than 0.15 mm/s, and complete gel breaking was achieved within 30 min without residues. For coal cores from the Qinshui Basin, the permeability recovery rate reached 78.6%. The permeability recovery rate of coal cores from the Qinshui Basin reached 78.6%. This fracturing fluid realizes viscosity enhancement and sand carrying via the worm-like micellar network formed by GEM-CBM, inducing minimal damage to CBM reservoirs and offering technical support for efficient CBM extraction. Full article

Mesoporous silica nanoparticles have been synthesized through sol–gel synthesis in basic conditions. Gemini surfactants having urea in the headgroups were used as pore-forming agents. The effect of the spacer length of the surfactant on the particle morphology was studied on the sub-micrometer and nanometer scales using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, and scanning and transmission electron microscopy (SEM, TEM). Depending on the spacer, spherical and/or cylindrical nanoparticles formed in different proportions, as revealed by statistical analysis of SEM micrographs. All prepared materials showed the hexagonal pore structure characteristic of the MCM-41 molecular sieves, with the exception of the sample prepared using the gemini surfactant with the shortest spacer length. The influence of the spacer length on the lattice parameter of the pore network, as well as the average size of the ordered domains, has been assessed by SAXS and TEM. Detailed analysis of the TEM images revealed a spread of the lattice parameter in a range of 10–20%. The broadening of the diffraction peaks was shown to be due to the combination of the effects of the finite domain size and the variance of the lattice parameter across the crystalline domains. The structural differences between the silica gels synthesized with the different surfactants were related to the variation of the micelle morphologies, reported in previous light scattering and small-angle scattering experiments. No connection could be revealed between the micelle shape and size and the pore sizes, showing that surfactants with a broad range of spacer lengths can equally well be used for the preparation of MCM-41 materials. Full article

Background/Objectives: Malignant neoplasms in children include leukemias. The main types are B-cell acute lymphoblastic leukemia (B-ALL) and acute myeloid leukemia (AML). Treatments are expensive, which is a particular problem in low-income countries. The main objective of this work was to develop specific nanosystems with small amounts of drug, allowing for affordable treatments. To this end, we designed ternary gold nanosystems (Au@16-Ph-16/DNA–Dauno) composed of daunomycin, a DNA biopolymer as a stabilizer, and the cationic surfactant gemini (TG) as a compacting agent for the DNA–daunomycin complex. Methods: Fluorescence, UV–visible, and CD spectroscopy, DLS and zeta potential, cell viability assays, TEM, AFM, and confocal microscopy were used to characterize and optimize nanocomposites. Results: The nanoparticles (Au@TG) obtained were small, stable, and highly charged in solution, allowing for optimal absorption and efficacy, capable of inducing the aggregation of the ternary nanosystem upon entering the cell, further enhancing its anticancer effect. Using nanoparticles, treatments can be redirected to the site of action, increasing the solubility and stability of the drug, minimizing the side effects of traditional treatments, and helping to overcome resistance to chemotherapy Conclusions: A significant decrease in the growth of pediatric B-ALL-derived cell lines (SEM and SUP-B15), constituting a potential and more affordable therapy for this type of pathology. Full article

To stimulate the progress of clean fracturing fluid systems, an innovative erucyl ultra-long-chain gemini surfactant (EUCGS) was devised and manufactured during the course of this study. The target product was successfully prepared via a two-step reaction involving erucyl primary amine, 3-bromopropionyl chloride, and 1,3-bis(dimethylamino)propanediol, with an overall yield of 78.6%. FT-IR and ¹H NMR characterization confirmed the presence of C₂₂ ultra-long chains, cis double bonds, amide bonds, and quaternary ammonium headgroups in the product structure. Performance tests showed that EUCGS exhibited an extremely low critical micelle concentration (CMC = 0.018 mmol/L) and excellent ability to reduce surface tension (γCMC = 30.0 mN/m). Rheological property studies indicated that EUCGS solutions gradually exhibited significant non-Newtonian fluid characteristics with increasing concentration, and wormlike micelles with a network structure could self-assemble at a concentration of 1.0 mmol/L. Dynamic rheological tests revealed that the solutions showed typical Maxwell fluid behavior and significant shear-thinning properties, which originated from the orientation and disruption of the wormlike micelle network structure under shear stress. In the presence of 225 mmol/L NaCl, the apparent viscosity of a 20 mmol/L EUCGS solution increased from 86 mPa·s to 256 mPa·s. A temperature resistance evaluation showed that EUCGS solutions had a good temperature resistance at high shear rates and 100 °C. The performance evaluation of fracturing fluids indicates that the proppant settling rate (0.25 cm/min) of the EUCGS-FFS system at 90 °C is significantly superior to that of the conventional system. It features the low dosage and high efficiency of the breaker, with the final core damage rate being only 0.9%. The results demonstrate that the EUCGS achieves a synergistic optimization of high-efficiency interfacial activity, controllable rheological properties, and excellent thermal–salt stability through precise molecular structure design, providing a new material choice for the development of intelligent responsive clean fracturing fluids. Full article

In this research work, the electrochemical evaluation of a non-ionic gemini surfactant as a green corrosion inhibitor for X100 pipeline steel in CO₂-saturated brine solution was carried out by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PPC). The corrosion inhibition performance of the gemini surfactant was studied in static and hydrodynamic conditions at room temperature and 60 °C. Electrochemical measurements showed that the inhibitor’s performance was enhanced with increasing inhibitor concentration and with increasing exposure time at room temperature, reaching the highest inhibition efficiency (η) at 100 ppm. With increasing temperature, the inhibitor efficiency decreased, with similar behavior at all concentrations. The analysis of the cathodic polarization curves at different rotation speeds showed the strong influence of mass transport on the cathodic process in the absence and the presence of the inhibitor. Under hydrodynamic conditions, PPC and EIS results indicated that the best inhibitor performance was with a concentration of 50 ppm, achieving a maximum inhibition efficiency of 91%. The adsorption of the inhibitor molecules on the surface obeyed the Langmuir isotherm, and the type of adsorption was mixed in all the study conditions. Surface characterization by scanning electron microscopy (SEM) revealed the formation of a protective corrosion inhibitor film. Full article

Cationic surfactants, accounting for approximately 7% of the global surfactant market, are widely used in applications such as fabric softeners, biocides, and corrosion inhibitors. Recently, gemini surfactants—comprising two amphiphilic units linked by a spacer—have attracted significant interest due to their superior surface activity, lower critical micelle concentrations, and strong antimicrobial properties. However, their poor biodegradability, resulting from their complex molecular structure, has raised environmental concerns. To address this, researchers have developed ester-based gemini surfactants incorporating biodegradable bonds. This study aimed to investigate the relationship between the structure of ester-based gemini surfactants (hydrophobic chain length and spacer type) and their antimicrobial activity against bacteria and fungi. Three series of compounds featuring different functional groups in the spacer were synthesized, along with a trimeric surfactant for comparative purposes. The results demonstrated that both the hydrophobic chain length and the presence of additional cationic groups significantly influence the CMC and antimicrobial performance. Quantum mechanical calculations were also performed to search for correlations between electronic properties and chemical reactivity of compounds. These findings highlight that ester-based gemini surfactants combine high surface and antimicrobial activity with the potential for improved biodegradability, making them promising candidates for use in environmentally friendly applications. Full article

To investigate the specific performance enhancement of oilfield surfactants by using sodium p-aminobenzenesulfonate as a connecting group, cationic surfactant N,N-dimethyl-N-(oxiran-2-ylmethyl)dodecan-1-aminium (DDPA) and zwitterionic gemini surfactant sodium 4-[bis(3-(dodecyldimethylamino)-2-hydroxypropyl)amino]benzenesulfonate (DDBS) were synthesized. The oil recovery performance of these surfactants was compared, revealing that DDBS outperforms DDPA in thermal stability, wettability, adsorption, and resistance to temperature and salinity variations, as well as surface/interface activity, except for emulsification. Core flooding experiments, simulating the conditions of the Xinjiang oilfield, demonstrated that DDBS can achieve the same enhanced oil recovery effect at a concentration that is 1/15 of that of DDPA. Compared with water, DDBS and DDPA can incrementally enhance recovery rates by 7.9% and 8.5%. Furthermore, the synergistic formulation of DDBS with sodium dodecylbenzenesulfonate (SDS) significantly optimized performance, achieving a reduction in interfacial tension to 0.0301 mN m⁻¹. This study provides a research and data foundation for the application of new surfactants in petroleum extraction. Full article

Background/Objectives: Mixed bloodstream infections associated with central venous catheter (CVC) use are a growing problem. The aim of this study was to evaluate the activity of a cationic arginine-based gemini surfactant, C₉(LA)₂, against mixed biofilms of fluconazole-resistant Candida albicans and extended-spectrum beta-lactamase (ESBL)-producing E. coli, and the preventive effect of this surfactant impregnated in CVCs on the formation of inter-kingdom biofilms. Methods: Broth microdilution assays were performed along with evaluation of the effect against mixed biofilms in formation. The impregnation of CVCs with the surfactant and with a hydrogel containing the cationic surfactant was investigated to assess their potential to prevent the formation of mixed biofilms. Scanning electron microscopy (SEM) was also utilized. Results: Minimum inhibitory concentrations (MICs) for resistant C. albicans ranged from 4–5.3 µg/mL, while for E. coli, the MICs varied from 85.3 to 298.7 µg/mL. Fungicidal and bactericidal action patterns were obtained. In mixed biofilm formation in 96-well plates, there was a significant reduction in the colony-forming unit (CFU) count. The impregnation of the CVC with C₉(LA)₂ alone resulted in a biofilm reduction of 62% versus C. albicans and 48.7% against E. coli in terms of CFUs. When the CVC was impregnated with the surfactant hydrogel, the effect was improved with an inhibition of 71.7% for C. albicans and 86.7% for E. coli. The images obtained by SEM corroborated the results. Conclusions: C₉(LA)₂ has potential for use in CVC impregnation to prevent the formation of mixed biofilms of fluconazole-resistant C. albicans and ESBL-producing E. coli. Full article

Mesoporous silica sieves have been prepared through sol–gel synthesis using diester gemini surfactants as pore templates, aiming to obtain new materials with potential use for water remediation. A series of mesoporous spherical silica particles of submicron size have been prepared in an alkali-catalyzed reaction, using a tetraethyl orthosilicate precursor and bis-quaternary ammonium gemini surfactants with diester spacers of varied lengths as pore-forming agents. The effect of the spacer length on the particle morphology was studied using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, scanning, and transmission electron microscopy (SEM, TEM). The results revealed that for all spacer lengths, a long-range hexagonal pore ordering developed in the materials. The silica particles were nearly spherical, with sizes below 1 micrometer, and a weak dependence of the mean particle size on the spacer length could be observed. The template removal procedure had a strong influence on the porosity: calcination caused a moderate shrinkage of the pores while retaining the hexagonal structure, whereas treatment with acidified ethanol resulted in only partial removal of the surfactants; however, the hexagonal structure was severely destroyed. The applicability of the obtained calcined materials as adsorbents for heavy metal ions from water was studied with the example of Pb(II). A high sorption capacity of 110 mg/g was obtained in batch experiments, at pH 5 and 4 h contact time. Full article

Cationic gemini surfactants are used due to their broad spectrum of activity, especially surface, anticorrosive and antimicrobial properties. Mixtures of cationic and anionic surfactants are also increasingly described. In order to investigate the effect of anionic additive on antimicrobial activity, experimental studies were carried out to obtain MIC (minimal inhibitory concentration) against E. coli and S. aureus bacteria. Two gemini surfactants (12-6-12 and 12-O-12) and two single quaternary ammonium salts (DTAB and DDAC) were analyzed. The most commonly used commercial compounds of this class, i.e., SDS and SL, were used as anionic additives. In addition, computer quantum mechanical studies were also carried out to confirm the relationship between the structure of the mixture and the activity. The obtained results of microbiological tests and quantum mechanical calculations are in agreement with each other and show the lack of synergism in catanionic mixtures in the case of antibacterial activity. Full article

The present work is devoted to the synthesis and analysis of the physicochemical properties of new functionalized asymmetric Gemini surfactants. Herein, alkyl- and azide-substituted surfactants with symmetric and asymmetric substituents were synthesized by using the click-reaction method. The critical aggregation concentration values of Gemini surfactants were determined. The binding processes of functionalized Gemini surfactants with bovine serum albumin were evaluated by fluorescence spectroscopy. Also, using the temperature dependences of the binding constants, the mechanism of Gemini surfactants binding with bovine serum albumin was studied. The hydrodynamic diameters of the formed bovine serum albumin/surfactant aggregates were analyzed. Based on electrophoretic light scattering, the ability of the synthesized Gemini surfactants to form associates was analyzed. The possibility of changing the mechanism of interaction in the 15c/bovine serum albumin system was shown. Based on the results obtained using different light scattering techniques and fluorescence spectroscopy, the mechanisms of interaction between bovine serum albumin and surfactants were determined. Full article

Three types of coatings (contact-based, release-based, and combined coatings with both contact-based and release-based actions) were prepared and tested for the ability to inactivate SARS-CoV-2. In these coatings, quaternary ammonium surfactants were used as active agents since quaternary ammonium compounds are some of the most commonly used disinfectants. To provide contact-based action, the glass and silicon surfaces with covalently attached quaternary ammonium cationic surfactant were prepared using a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride modifier. Surface modification was confirmed by attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and contact angle measurements. The grafting density of the modifier was estimated by XPS and elemental analysis. To provide release-based action, the widely used quaternary ammonium cationic disinfectant, benzalkonium chloride (BAC), and a newly synthesized cationic gemini surfactant, C18-4-C18, were bound non-covalently to the surface either through hydrophobic or electrostatic interactions. Virus titration revealed that the surfaces with combined contact-based and release-based action and the surfaces with only release-based action completely inactivate SARS-CoV-2. Coatings containing only covalently bound disinfectant are much less effective; they only provide up to 1.25 log10 reduction in the virus titer, probably because of the low disinfectant content in the surface monolayer. No pronounced differences in the activity between the flat and structured surfaces were observed for any of the coatings under study. Comparative studies of free and electrostatically bound disinfectants show that binding to the surface of nanoparticles diminishes the activity. These data indicate that SARS-CoV-2 is more sensitive to the free disinfectants. Full article

The solubilization behavior of medroxyprogesterone (MP) within gemini surfactant micelles (14-6-14,2Br⁻) was investigated and compared with that of progesterone to uncover distinct solubilization mechanisms. We employed ¹H-NMR and 2D ROESY spectroscopy to elucidate the spatial positioning of MP within the micelle, revealing that MP integrates more deeply into the micellar core. This behavior is linked to the unique structural features of MP, particularly its 17β-acetyl group, which promotes enhanced interactions with the hydrophobic regions of the micelle, while the 6α-methyl group interacts with the hydrophilic regions of the micelle. The 2D ROESY correlations specifically highlighted interactions between the hydrophobic chains of the surfactant and two protons of MP, H22 and H19. Complementary machine learning and electron density analyses supported these spectroscopic findings, underscoring the pivotal role of the molecular characteristics of MP in its solubilization behavior. These insights into the solubilization dynamics of MP not only advance our understanding of hydrophobic compound incorporation in gemini surfactant micelles but also indicate the potential of 14-6-14,2Br⁻ micelles for diverse drug delivery applications. Full article