Series Of Cationic Gemini Surfactants Research Articles

O/D emulsions stabilized by quaternary ammonium gemini surfactants together with alumina nanoparticles

AbstractOil‐in‐dispersion (O/D) emulsions are the focus in many fields due to their new microstructures and new functions. Herein, O/D emulsions were successfully prepared using series of cationic gemini surfactants 12‐s‐12 (s = 2, 3, and 6) and alumina nanoparticles. The microstructures and type of emulsions were identified using optical microscopy, zeta potential and contact angle methods. Gemini surfactants with two head groups carry more charges than that of conventional surfactants when adsorbed at the oil–water interface. The O/D emulsions can be stabilized at lower surfactant concentrations compared with the conventional single‐headed surfactants. In the presence of 0.1 wt% alumina nanoparticles, gemini surfactants 12‐s‐12 (s = 2, 3, and 6) can stabilize emulsions at the concentration of 3 × 10−4 mM (1.84 × 10−5 wt%), 6 × 10−4 mM (3.76 × 10−5 wt%) and 1 × 10−3 mM (6.68 × 10−5 wt%), respectively. Addition of excessive organic salts such as sodium salicylate and sodium p‐methylbenzenesulfonate shielded the head group charges of gemini surfactants, leading to gemini surfactants to behave as nonionic surfactants Adsorption of surfactants at the alumina nanoparticles occurred, resulting in the transformation from the O/D emulsions to Pickering emulsions. This work shows the advantages of preparing O/D emulsions using gemini surfactants and also provides a new methods of emulsion type transformations by adding excessive oppositely charged organic salts.

A study involving PC-3 cancer cells and novel carbamate gemini surfactants: Is zeta potential the key to control adhesion to cells?

Liposome surface potential effect on cellular uptake and cytotoxicity is evaluated using liposomes, modified with cationic lipid DOTAP, a series of cationic gemini surfactants with two carbamate fragments, and an amphiphilic peptide SSRGD. The surfactants used are novel representatives of the gemini family with improved self-assembling activity coupled with potential biodegradable properties and displayed increasing antibacterial activity and cytotoxicity with the shortening of hydrophobic alkyl tails. The longest alkyl tail surfactant, 14-6-14(Et), was the most biocompatible of the series, which was chosen for liposome modification. Prepared liposomes of various compositions are characterized from morphological and physicochemical standpoints in order to optimize their biocompatibility and stability. The carbamate gemini surfactants were also twice as effective at providing positive charge to liposomes and less toxic compared to DOTAP. On their own, carbamate surfactants were able to increase cellular uptake of liposomes by 190%. The mixed composition of 14-6-14(Et) surfactant and SSRGD amphiphilic peptide was the most readily absorbed formulation among different tested neutral, cationic and RGD-modified liposomes. The comparison between the cellular uptake promotion is conducted as to what is the most selective and efficient approach to enhance lipid nanoparticle uptake by cancerous cells.

Role of Different States of Solubilized Water on Solvation Dynamics and Rotational Relaxation of Coumarin 490 in Reverse Micelles of Gemini Surfactants, Water/12-s-12.2Br- (s = 5, 6, 8)/n-Propanol/Cyclohexane.

The present study demonstrates how the different states of solubilized water viz. quaternary ammonium headgroup-bound, bulklike, counterion-bound, and free water in reverse micelles of a series of cationic gemini surfactants, water/12-s-12 (s = 5, 6, 8).2Br–/n-propanol/cyclohexane, control the solvation dynamics and rotational relaxation of Coumarin 490 (C-490) and microenvironment of the reverse micelles. The relative number of solubilized water molecules of a given state per surfactant molecule decides major and minor components. A rapid increase in the number of bulklike water molecules per surfactant molecule as compared to the slow increase in the number of each of headgroup- and counterion-bound water molecules per surfactant molecule with increasing water content (Wo) in a given reverse micellar system is responsible for the increase in the rate of solvation and rotational relaxation of C-490. The increase in the number of counterion-bound water molecules per surfactant molecule and the concomitant decrease in the number of bulklike water molecules per surfactant molecule with increasing spacer chain length of gemini surfactants at a given Wo are ascribed to the slower rates of both solvation and rotational relaxation. Relative abundances of different states of water have a role on the microenvironment of the reverse micelles as well. Thus, a comprehensive effect of different states of water on dynamics in complex biomimicking systems has been presented here.

Applications of Molecular Structural Aspects of Gemini Surfactants in Reducing Nanoparticle–Nanoparticle Interactions

Oppositely charged nanoparticle (NP)-nanoparticle (NP) interactions were studied by titrating sodium dodecyl sulfate (SDS) stabilized NPs with cetyltrimethylammonium bromide (CTAB) stabilized NPs at constant temperature with the help of UV-visible and dynamic light scattering measurements. CTAB stabilized NPs were systematically replaced with a series of cationic gemini surfactants to demonstrate the effect of head group and hydrocarbon tail modifications on the electrostatic interactions with SDS stabilized NPs. Introduction of the dimeric gemini head group (alkylammonium or imidazolium), spacer length, and double tail hydrocarbon length all significantly reduced the NP-NP interactions and delayed their salting-out process. They lead to the formation of stable colloidal aqueous solubilized NP-NP complexes. The results concluded that NP-NP interactions can be overcome if appropriately stabilized NPs are used to maintain their colloidal stability so as to achieve maximum applicability.

Study on mechanism of Gemini surfactant inhibiting acid rock reaction rate

Inhibiting acid-rock reaction rate is an important key in the field of acid fracturing. Based on the acid-rock reaction mechanism and the performance characteristics of surfactant, the surfactant is applied to cover the rock surface for forming an adsorption layer, which can keep H+ from contacting the surface of rock during acid fracturing. In this paper, a series of cationic Gemini surfactants with different hydrophobic chain length are synthesized (Cn-4-Cn, n = 12, 14, 16).The surface tension, adhesion work, and AFM are used to investigate the effect of hydrophobic chain length and concentration of surfactant on surface activities, adsorption morphology and adsorption capacities. The static acid-rock reaction rate is measured and the surface of the rock plate is digitally characterized by 3D scanning. The results show that Gemini surfactants have the high surface activities. It can be recognized from AFM that as the length of the carbon chain increases, the aggregation of Gemini surfactants on the surface to form micelles becomes more and more obvious, resulting in a decrease in the density and area of the adsorption. However there are few differences for adsorption capacities. Therefore, 12-4-12 can restart H+ most efficiently. This conclusion is proved by static acid-rock reaction. In addition, H+ only reacted with the rock from the micro fractures of the adsorption layer formed by 12-4-12, the surface morphology of the rock plate after etching is the best rugged. In conclusion, it is believed that using the Gemini surfactant to form an adsorption layer on the rock surface is a new approach for inhibiting acid rock reaction rate and has great potential in oil field application.

Micellization and Adsorption Properties of New Cationic Gemini Surfactants Having Hydroxyisopropyl Group

A series of cationic gemini surfactants, N,N′-bis(alkyl)-N,N′-bis(2-hydroxypropyl)ethylenediammonium dibromide, [CnH2n+1(CH3CH(OH)CH2)NH(CH2)2NH(CH2CH(OH)CH3)CnH2n+1]Br2 (where n is the tail chain length, n = 9, 12, and 14), referred to as CnC2Cn[iso-Pr(OH)] was synthesized. Via conductometric and tensiometric methods, at different temperatures (283 to 313 K), specific electrical conductivities and surface tensions of the aqueous solutions of these cationic gemini surfactants were determined. According to the obtained values, micellization and adsorption parameters such as critical micellization concentration (CMC), maximum surface excess (Γmax), minimal cross sectional surface area of surfactant polar group (Amin), adsorption efficiency (pC20), surface pressure (π), and binding degree of counterion (β) were calculated. The values of standard Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were also computed. Via the dynamic light scattering method, diameters of aggregates of the synthesized ca...

Seeded growth of gold nanoparticles in aqueous solution of cationic gemini surfactants with different spacer length: influences of molecular and aggregate structures

It is well known that surfactants play a vital role in aqueous-phase synthesis of gold nanoparticles (GNPs). However, to date, it remains challenging to fully elucidate the roles of surfactants, especially for the correlation between the molecular and aggregate structure of the employed surfactant and the structures of the resulting GNPs. In the study, the synthesis of GNPs in aqueous solution of a series of cationic gemini surfactants with different spacer length (12-s-12, s = 0, 2, 4, 6, 8, 10, and 12) has been investigated. A remarkable spacer length-dependent morphological evolution of nanorod→nanostar→nanoplate→spherical nanoparticle has been observed. The results show that the gemini surfactants can form the electrostatic complexes with AuI ions, and the complexes further self-assemble into the various aggregates of different sizes, which greatly alters the migration dynamics of AuI and eventually influences the growth kinetics of GNPs. The overall growth rate of the GNPs is determined by the combination of the monomer-AuI molecular weight, the size of aggregates, and the local concentration of AuI in the aggregates. Besides, the gemini surfactants with different spacer length could selectively anchor on various facets of GNPs, thus acting as the capping agents to direct the formation of the shaped GNPs. It is believed that the cationic gemini surfactants with different spacer length provide an excellent choice to control the growth kinetics and final morphology of GNPs, and this study provides new insights in surfactant-assisted synthesis of GNPs.

Enhanced oil recovery from high‐salinity reservoirs by cationic gemini surfactants

ABSTRACTIn order to enhance oil recovery from high‐salinity reservoirs, a series of cationic gemini surfactants with different hydrophobic tails were synthesized. The surfactants were characterized by elemental analysis, infrared spectroscopy, mass spectrometry, and 1H‐NMR. According to the requirements of surfactants used in enhanced oil recovery technology, physicochemical properties including surface tension, critical micelle concentration (CMC), contact angle, oil/water interfacial tension, and compatibility with formation water were fully studied. All cationic gemini surfactants have significant impact on the wettability of the oil‐wet surface, and the contact angle decreased remarkably from 98° to 33° after adding the gemini surfactant BA‐14. Under the condition of solution salinity of 65,430 mg/L, the cationic gemini surfactant BA‐14 reduces the interfacial tension to 10−3 mN/m. Other related tests, including salt tolerance, adsorption, and flooding experiments, have been done. The concentration of 0.1% BA‐14 remains transparent with 120 g/L salinity at 50 °C. The adsorption capacity of BA‐14 is 6.3–11.5 mg/g. The gemini surfactant BA‐14 can improve the oil displacement efficiency by 11.09%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46086.

Silver Nanoparticles Stabilised by Cationic Gemini Surfactants with Variable Spacer Length.

The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of variable length. UV-VIS spectroscopy, dynamic light scattering, scanning electron microscopy and zeta potential measurements were applied to provide physicochemical characterization of the silver nanoparticles. The mean size values of the nanoparticles were found to be in the 50 to 115 nm range. From the nanoparticle size distributions and scanning electron microscopy images it results that a population of small nanoparticles with the size of several nanometers was confirmed if the nanoparticles were stabilized with gemini molecules with either a short methylene spacer (two or four −CH2− groups) or a long spacer (12 −CH2− groups). The average zeta potential value for silver nanoparticles stabilized with gemini molecules is roughly independent of gemini surfactant spacer length and is approx. +58 mV. An interaction model between silver nanoparticles and gemini molecules which reflects the gained experimental data, is suggested. Microbicidal activity determinations revealed that the silver nanoparticles stabilized with gemini surfactants are more efficient against Gram-negative bacteria and yeasts, which has a direct relation to the interaction mechanism of nanoparticles with the bacterial cell membrane and its structural composition.

Surface Activities and Quantum Chemical Calculations for Different Synthesized Cationic Gemini Surfactants

Abstract Three series of cationic gemini surfactants were prepared and characterized using elemental analysis and 1H-NMR spectroscopy. The surface properties of them, critical micelle concentration (CMC), surface excess concentration (Γmax) and minimum surface area per molecule (Amin) were evaluated via surface tension measurements. Quantum chemical parameters, such as the energy of the highest occupied molecular orbital (EH), the energy of the lowest unoccupied molecular orbital EL, the energy gap (ΔEg), dipole moment (μ), electronegativity (χ), hardness (η), electrophilicity (ω), hydrophobicity (Log P), approximated surface area (A) and the total energy of the optimized structure (ΔET), were theoretically calculated using the MNDO method.

Synthesis and properties of biodegradable cationic gemini surfactants with diester and flexible spacers

A series of cationic gemini surfactants with diester and flexible spacers, namely C12-PG-C12, C14-PG-C14 and C16-PG-C16, were synthesized, purified and characterized. The surface properties and aggregation behavior of the gemini surfactants were investigated by surface tension, electrical conductivity, fluorescence and Krafft point. These gemini surfactants possess higher surface activity than the traditional monomeric surfactants. The thermodynamic parameters exhibited that the micellization was a spontaneous and exothermic process in environment. The micellization process became less favorable with the decrease of alkyl chain length and the increase of temperature. Steady-state fluorescence measurements revealed that the micropolarity and aggregation number of micelles decreased with the increase of hydrocarbon chain length. The Krafft points were taken as <0°C, which indicated the synthesized gemini surfactants had good water solubility. The biodegradability of the gemini surfactants were evaluated in river water using Closed Bottle tested and showed their high biodegradation ratio in the open environment due to the diester bond inserting in the flexible spacer of surfactant molecules.

Self-assembly properties of ultra-long-chain gemini surfactants bearing multiple amide groups with high performance in fracturing fluid application

In this work, a series of cationic gemini surfactants (C25-alkyl-C25, C25-ester-C25 and C25-amide-C25), which possessed a special structure consisting of ultra-long hydrophobic chains and cleavable groups, were synthesized using a main feedstock source obtained from rapeseed and applied as viscoelastic surfactant (VES) fracturing fluids in high temperature formations. Surface activities, rheological behavior analysis, scanning electron microscope (SEM) and cryogenic transmission electron microscopy (cryo-TEM) observations, and fracturing fluid performance were performed to determine the solution properties of gemini surfactants in the presence of ammonium chloride (NH4Cl). The results showed that the order of the critical micelle concentration (CMC) value was C25-alkyl-C25<C25-ester-C25<C25-amide-C25. And their ΔGmic0 values were found to have negative values, indicating that their self-assembly processes were spontaneous. The three surfactant/NH4Cl fluids exhibit high viscoelasticity and three-dimensional (3D) network structure. The 20mmolL−1 C25-ester-C25 fluid containing 0.19molL−1 NH4Cl meets the demands of a fracturing operation under 100°C, so do C25-alkyl-C25/NH4Cl and C25-amide-C25/NH4Cl fluids. In particular, the highest applicable temperature of the C25-amide-C25/NH4Cl system can reach to 150°C. Hence, C25-amide-C25 is a very promising candidate material for VES fracturing fluids.

Synthesis and Evaluation of Bis‐quaternary‐Based Surfactants as Additives for Water‐Based Mud

AbstractTwo series of cationic gemini surfactants, alkanediyl‐α,ω‐bis[N,N‐dimethyl alkyl (octyl or dodecyl)ammonium] dibromide (R‐s‐R; s = 6, 10, 12 and R = 8 and 12) were prepared and evaluated as additives for water‐based mud. The chemical structures of the prepared surfactants were confirmed using FTIR and mass spectroscopy. Surface activity of these compounds has been studied and their surface properties including surface tension, emulsification power, critical micelle concentration, effectiveness, maximum surface excess and minimum surface area were determined. The results showed that the prepared compounds have significant surface activity, especially those of longer hydrophobic chain length. The prepared cationic gemini surfactants were evaluated as viscosifiers and filter loss additives for water‐based mud formulated from local Na‐montmorillonite clay. XRD analysis was carried out to the Na‐montmorillonite clay to determine the interaction of the surfactants with inter layers of the clay structure. Rheological properties, gel strength, thixotropy, filtration properties and the effect of temperature on rheological properties of the water‐based mud were studied. The results indicated that the gemini surfactants have a positive effect on the rheological and filtration properties of the Na‐montmorillonite clay according to American Petroleum Institute specifications.

Synthesis, interface activity and oil flooding experiment with an authentic sandstone microscopic model of cationic gemini surfactant

ABSTRACTIn this work, a series of cationic gemini surfactants with different hydrophobic tails were prepared and characterized by element analysis, IR spectra, and 1H NMR spectra. The influencing factors of physic-chemical properties of these surfactants were carefully studied. The critical micelle concentration (CMC) of all the surfactants ranged from 3.87 × 10−4 mol L−1 to 8.97 × 10−4 mol L−1 and the values (γcmc) also ranged from 28.62 mN m−1 to 34.07 mN m−1 at CMC level by surface tension experiments. The consequences of the oil/water interface tension experiments indicated that all these prepared surfactants could lower oil/water interface tension to ultra-low with the combination of Na2CO3. C12-2-C12, and C14-2-C14 were chosen as the representative to evaluate the displacement efficiency in the oil flooding experiments using authentic sandstone microscopic model. The results showed that these surfactants could effectively improve the displacement efficiency by 10–20%.

Effects of Interaction of Gemini Ester Quat Surfactants with Biological Membranes

Abstract The aim of the study was to determine the relation between the biological activity of two homologous series of cationic gemini surfactants, which are quaternary ammonium salts, and their structure. The measure of the biological activity of the compounds was assumed to be the effects they exert on the membrane of erythrocytes, treated as a simple model of the biological membrane. In particular, it was determined the effects of the compounds on hemolysis and the osmotic resistance of erythrocytes and the fluidity of erythrocyte membrane, and the packing arrangement of the polar heads of membrane lipids. The results have shown that surfactants affect the osmotic resistance of erythrocytes to various degrees, and at sufficiently high concentrations operate destructively on their membrane, eventually causing hemolysis, modify the fluidity of erythrocyte membrane and affect the arrangement of polar heads of membrane lipids. Additionally, the results showed that that activity depends on a surfactant's chemical structure, in particular, on the length of its alkyl chain and structure of the polar head group that determines the spacing between the chains. In both used new series the compounds containing 10, 12 and 14 carbon atoms in a chain possess a high biological activity. In addition, the surfactants with larger spaces between the chains are more active than those with smaller spacing. The investigations have revealed a high activity of compounds with longer chains and bigger polar heads. The results of the study may find application when designing a molecular structure and synthesizing new compounds of specific, desired activity.

Wettability of coal pitch surface by aqueous solutions of cationic Gemini surfactants

Abstract The purpose of this experiment is to confirm the adsorption characteristics at liquid–gas and CP–liquid interfaces in relation to CP wetting with a sequence of cationic Gemini surfactant solutions and to reduce the workload of screening of surfactant. A series of cationic Gemini surfactants with different hydrophobic chain length was synthesized (C n -8-C n , n = 8, 10, 12, 14, 16). Their wettability and adsorption mechanism for coal pitch (CP) were investigated by the sessile drop analysis and electrophoresis. Within the whole range of concentration, the Zisman theory is not in accordance with the wettability on the coal tar pitch when carbon atoms of hydrophobic chains exceed 12. Meanwhile, no liner dependence was observed between adhesion tension ( γ lg cos θ ) and surface tension ( γ lg ). In addition, with the increase of surfactant concentration, Zeta potential on the surface of the CP changed from negative to positive and finally leveled off after a certain concentration. The corresponding concentration of zero potential was at least an order of magnitude lower than CMC. C 12 -8-C 12 can significantly change the wettability of the CP. According to the wetting data and Zeta potential of Gemini surfactant on CP, it can be inferred that wetting was a concerted action as a result of electrostatic interaction and van der waals adsorption. Therefore, wetting process can be generally divided into three stages.

Solvation dynamics and rotational relaxation of coumarin 153 in mixed micelles of Triton X-100 and cationic gemini surfactants: effect of composition and spacer chain length of gemini surfactants.

Solvation dynamics and rotational relaxation of coumarin 153 (C-153) in mixed micelles of non-ionic surfactant, Triton X-100 and a series of cationic gemini surfactants, 12-s-12, 2Br with varying polymethylene spacer chain length (s = 3, 6, 8, 12) at different bulk mole fractions of a surfactant were studied. Studies were carried out by means of UV-Vis absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, and dynamic light scattering measurements. While micropolarity of the environment around C-153 in mixed micelles increased, the microviscosity decreased with increasing amount of a gemini surfactant. This is because the thickness of the Stern layer of micelles increases as a result of greater extent of penetration of water molecules. Solvation dynamics and rotational relaxation of C-153 become faster with increasing mole fraction of a gemini surfactant in the mixed micelles. Increasing the thickness of the Stern layer leads to an increase in the number of water molecules hydrogen bonded among themselves, resulting in an increase in polarity and microfluidity of the environment. At a given bulk mole fraction of a surfactant, the microviscosity of micelles decreases with increasing the spacer chain length of the gemini surfactant resulting in an increase in the rate of the rotational relaxation process. However, at a given bulk mole fraction of a surfactant, solvation dynamics becomes slower with increasing spacer chain length from s = 3 to 8 because of the increasing degree of counter ion dissociation. The slow rotational relaxation process is mainly due to the lateral diffusion of C-153 along the surface of the micelles. Rotationalmotion of the micelle as a whole is much slower than the lateral diffusion of C-153.

Effect of Polymethylene Spacer of Cationic Gemini Surfactants on Solvation Dynamics and Rotational Relaxation of Coumarin 153 in Aqueous Micelles.

The present work demonstrates the solvation dynamics and rotational relaxation of Coumarin 153 (C-153) in the micelles of a series of cationic gemini surfactants, 12-s-12, 2Br(-) containing a hydrophobic polymethylene spacer with s = 3, 4, 6, 8, 12. Steady-state and time-correlated single-photon counting (TCSPC) fluorescence spectroscopic techniques have been used to carry out this study. Steady-state and TCSPC fluorescence data suggest that C-153 molecules are located at the Stern layer of micelles. While probe molecules feel more or less the same micropolarity in the micellar phase, the microviscosity of micelles decreases with spacer chain length. Solvation dynamics at the Stern layer is bimodal in nature with fast solvation as a major component. Counter ions and water molecules bonded with the polar headgroups of surfactant molecules are responsible for the slow component. Average solvation time increases with spacer chain length because of the increased degree of counter ion dissociation. Some water molecules are involved in the solvation of counter ions themselves, resulting in the decrease in "free" water molecules to be available for the solvation of C-153. The hydrophobic spacer chain also has an effect on increasing the solvation time with increasing chain length. The average rotational relaxation time for C-153 decreases with spacer chain length with a rapid decrease at s > 4. The anisotropy decay of C-153 in micelles is biexponential in nature. The slow rotational relaxation is due to the lateral diffusion of C-153 in micelles. Lateral diffusion is much faster than the rotational motion of a micelle as a whole. The rotational motion of the micelle as a whole becomes faster with the decreasing size of micelles.

Surface properties and aggregation behavior of cationic gemini surfactants with dipropylammonium head-groups

Abstract A series of cationic gemini surfactants, butane-α,δ-bis-(dipropyl alkyl ammonium bromide), [CnH2n+1(CH3CH2CH2)2N(CH2)4N(CH3CH2CH2)2CnH2n+1]Br2 (where n is the tail chain length, n = 10, 12, 14, and 16), referred to as CnC4Cn(Pr) were synthesized. The surface properties and aggregation behavior of these surfactants were investigated by measuring their surface tension, electrical conductivity, fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM). These gemini surfactants CnC4Cn(Pr) have a lower critical micelle concentration (CMC) than their corresponding monomer surfactants. Solution electric conductivity measurements indicated that premicellar aggregations were found in the C16C4C16(Pr) solution. Steady-state fluorescence measurements revealed that the C16C4C16(Pr) surfactant formed noncompact aggregate structures in solution over a wide concentration range. Interestingly, dynamic light scattering and transmission electron microscopy studies showed that the aggregations of the four surfactants were vesicle, which is not in accordance with the critical packing parameter (P) values obtained from Tanford's equation. To explain this unusual phenomenon, the volume of the component groups was used to calculate the hydrophobic volume and it was assumed that this phenomenon probably resulted from the face-to-face hydrophobic chains of these gemini surfactant molecules were inclined to be interdigitized in the aggregate.

Antibacterial Activities of Five Cationic Gemini Surfactants with Ethylene Glycol Bisacetyl Spacers

AbstractA series of cationic gemini surfactants containing two dimethylalkylammonium chains linked by ethylene glycol bisacetyl spacers were synthesized [Gm‐AnA‐m, G = gemini surfactant, m = 12 (–C12H25), 14 (–C14H29), or 16 (–C16H33), A = acetyl, and n = 2, 3, or 4 is the number of ethylene glycol units in the spacers]. Because of the inductive effect of the oxygen atom in the spacer, acylation can take place using chloroacetyl chloride instead of bromoacetyl bromide which helps to limit the use of environmentally harmful reagents. Critical micelle concentrations were determined using conductivity measurements. The antibacterial activities of the surfactants against Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated from the minimum inhibitory concentration (MIC), minimum bacterial concentration, a time–kill study, and the inhibitory zone. Increasing the length of the spacer did not result in an obvious change of antibacterial activity. However, increasing the length of the alkyl chain apparently increased the antibacterial activity against S. aureus but decreased the antibacterial activity against E. coli. The G12‐A2A‐12 surfactant had the lowest CMC of 1.26 mmol L−1 and exhibited the best antibacterial activity with a MIC of 32 μg mL−1 toward S. aureus and 64 μg mL−1 toward E. coli in the presence of 105 CFU of bacteria. This work indicated that these cationic gemini surfactants have potential applications as antibacterial agents and emulsifiers.