Cationic Gemini Surfactants Research Articles

Effects of Fructose and Temperature on the Micellization of a Cationic Gemini Surfactant, Pentanediyl-1,5-bis(dimethylcetylammonium) Bromide in Aqueous Solutions

By the conductivity measurements the effects of fructose and temperature (293–308 K) on the micellization of a cationic gemini surfactant (GS), pentanediyl-1,5-bis(dimethylcetylammonium) bromide in aqueous solutions have been investigated. The critical micelle concentration (CMC) of GS was measured at the different temperatures and fructose concentrations. An increasing trend of the CMC values is with addition of fructose. With increasing temperature, the CMC values are in a similar increasing trend. The CMC of GS by dye solubilization method at room temperature have been determined. The standard Gibbs energy, enthalpy and entropy of GS micellization have been evaluated. From these thermodynamic parameters, it was found that in presence of fructose, the stability of the GS aqueous solutions decreases.

Adsorption of anionic azo dyes from aqueous solution on cationic gemini surfactant-modified flax shives: Synchrotron infrared, optimization and modeling studies

There is an emerging interest in using biomass waste for environmental applications. In this study, the flax shives modified by cationic gemini surfactant (MFS) were used for the removal of anionic azo dyes from aqueous solution. Response surface methodology (RSM) was used to determine the optimal modification conditions. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS was conducted. The adsorption equilibrium data were well fit by the Langmuir model. The adsorption process followed the pseudo-second-order and Elovich models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous and exothermic. The adsorption of acidic azo dyes on MFS was influenced by temperature, initial pH, MFS dosage and ionic strength. The interactions of these four factors were further investigated through a two-level full factorial design. The results can help better understand the transport behaviors of organic pollutants at biomass adsorbent-water interface. It also presents the potential of MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

Rheology and high-temperature stability of novel viscoelastic gemini micelle solutions

ABSTRACTTo broaden the application of clean fracturing fluid based on surfactant, a gemini cationic C25-tailed surfactant, called FL-25, was synthesized. FL-25 can form a wormlike viscoelastic fluid in aqueous solution without adding any organic or inorganic salts. The rheological properties and thermal stability of the novel gemini micelle solutions were further investigated. The results show that the gemini micelle solution possesses viscoelasticity, thixotropy, and shear-thinning properties. The apparent viscosity of the viscoelastic gemini micelle solution at a shear rate of 170 s−1 remains approximately 69 mPa · s at 110°C for 90 minutes, showing good high-temperature-resistance property. FL-25 may be a novel gemini surfactant applied in clean viscoelastic surfactant fracturing fluids in the oil and gas field.

Fabrication of pH-responsive system based on cationic gemini surfactant/sodium octanedioate and its application on controlled release of paclitaxel

A pH-responsive surfactant system has been self-assembled between a cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and sodium octanedioate (C8Na2), which was characterized by surface tension, proton nuclear magnetic resonance (1H NMR), dynamic light scattering (DLS), transmission electronic microscopy (TEM) and fluorescence probe spectroscopy. The interaction between 12 and 6–12 and C8Na2 are based on the electrostatic and hydrophobic interaction as evidenced by surface tension and 1H NMR. The self-assembled 12-6-12/C8Na2 system has been demonstrated to be concentration dependence and pH dependence. With increasing the concentration of C8Na2, the vesicle form of 12-6-12 can transform to micelles. Vesicle-to-micelle transition of the 12-6-12/C8Na2 aggregates is reversible with tuning the pH values. The micropolarity inside the 12-6-12/C8Na2 aggregates was characterized by fluorescence spectroscopy using pyrene as probe, indicating that the micropolarity is enhanced with the increased pH. Furthermore, the release assay of an oil-soluble drug paclitaxel performs well in this pH-responsive surfactant system and the drug releasing rate could be controlled by pH values.

Multiple spectroscopic studies of the interaction between a quaternary ammonium-based cationic Gemini surfactant (as a carrier) and human erythropoietin

Erythropoietin (EPO) is a hematopoietic growth factor. This substance, as a strong cell protector, can increase cell maintenance during different damages of central nervous system. Since the brain-blood barrier prevents the entrance of large proteins similar to EPO into the brain, its systemic delivery gets limited. The aim of this study was to find an alternative approach for EPO delivery into the brain to skip the blood-brain barrier prevention. So, a new quaternary ammonium-based cationic Gemini surfactant has been used to study the interaction of the cationic Gemini surfactant (as a carrier) with EPO using various spectroscopic techniques of (fluorescence and circular dichroism (CD)) and thermal denaturation. Fluorescence spectroscopy studies show the formation of Gemini-EPO complex and also static quenching of protein upon this interaction. The binding parameters of number of binding sites, binding affinity, Gibbs free energy, enthalpy, and entropy were calculated according to fluorescence quenching studies. Also, CD results have further represented that the content of regular secondary structure of EPO did not show any significant alterations by increasing the Gemini concentration. Finally, thermal denaturation behavior of EPO results indicates decreasing the thermal stability of protein in the presence of Gemini. In conclusion, the obtained results proposed that Gemini as a cationic surfactant can bind to EPO without any significant diverse effects on the structure of this drug (EPO) which can be considered as a candidate for EPO delivery in future.

Aggregation of a Cationic Gemini Surfactant with a Chelating Molecule and Effects from Calcium Ions.

The aggregation behavior of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) with chelating molecule ethylenediaminetetraacetic acid (EDTA) and the effects of calcium bromide (CaBr2) on the structure and morphology of the aggregates in the mixture have been investigated by surface tension, isothermal titration microcalorimetry, electrical conductivity, ζ potential, dynamic light scattering, cryogenic transmission electron microscopy, freeze-fracture transmission electron microscopy, and 1H NMR techniques. It was found that the electrostatic attraction between the carboxyl groups of EDTA and the headgroups of 12-6-12 leads to the formation of oligomeric-like surfactant EDTA(12-6-12)2 at an EDTA/12-6-12 molar ratio of 0.50. The critical aggregation concentration of the EDTA(12-6-12)2 complexes is much lower than that of 12-6-12, and the complexes form loose, large network-like premicellar aggregates and then transfer into small micelles with an increase in concentration. Moreover, the addition of CaBr2 induces the transition from the loose aggregates and micelles to vesicles owing to the coordination interaction between the calcium ion and EDTA and the electrostatic interaction between EDTA and 12-6-12. The work reveals that as a bridging molecule between the calcium ion and the gemini surfactant, the chelating molecule greatly promotes the assembly of the gemini surfactant and strengthens the molecular packing in the presence of calcium ions.

Interaction of oxy-diester-linked cationic gemini surfactants with nonionic amphiphiles in aqueous medium

We have investigated the interaction of nonionic conventional surfactants, Brij 35 and Brij 58, with three homologous oxy-diester-linked cationic gemini surfactants, 2,2′-[(oxybis(ethane-1,2-diyl))bis(oxy)]bis(N-alkyl-N,N-dimethyl-2-oxoethanaminium) dichloride (C m -DEG-C m , m = 12, 14, 16), by the surface tension measurements at 30 °C. The tensiometric data were used to calculate the critical micelle concentration (cmc) of the pure and mixed (equimolar) gemini–conventional surfactant systems. cmc values of the gemini surfactants are well below those of their monomeric counterparts which contain the same number of carbon atoms in the hydrophobic tail per polar head group. From the experimentally obtained cmc values of the binary surfactant mixtures (1:1), various physicochemical parameters were calculated. Lower cmc values of the binary solutions than the ideal cmc and also the negative β m values indicate that the interactions between the component surfactants of the mixed systems are synergistic in nature; the C16-DEG-C16 + Brij 58 system is an exception, in which antagonism is observed. The occurrence of mixed micellization is indicated by the decrease in cmc of the binary surfactant solutions and nonideality of the mixed systems. Interaction parameters (β m , β σ ) of the mixed systems were evaluated by using the theoretical models suggested by Clint, Rubingh, and Rosen. Negative values of β and $$ \varDelta {G}_{\mathrm{ex}}^m $$ (excess free energy of mixing) indicate an overall attractive force in the mixed state. The cationic gemini surfactant with lower chain length shows higher interaction with the nonionic conventional surfactants.

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.

Effects of 1-alkyl-3-methylimidazolium bromide ionic liquids on the micellar properties of [butanediyl-1,4-bis(dimethyldodecylammonium bromide)] gemini surfactant in aqueous solution

The micellar properties of the cationic gemini surfactant [butanediyl-1,4-bis (dimethyldodecylammonium bromide)] (12-4-12) were investigated at 298.15 K in the presence of 1-R-3-methylimidazolium bromide ionic liquids (ILs, R = 1-butyl, 1-(1-butyl)-3-methylimidazolium bromide (BuMeImBr); 1-hexyl, 1-(1-hexyl)-3-methylimidazolium bromide (HxMeImBr); and 1-octyl, 1-(1-octyl)-3-methylimidazolium bromide (OcMeImBr)), present as additives. The emphasis was on c(IL) (0.2 to 1 wt%) and the length of R. The following techniques were employed: conductivity, surface tension, UV-Vis, fluorescence spectroscopy of solubilized compounds, and dynamic light scattering (DLS). For the ILs, values of the critical micelle concentration, critical micellar concentration (cmc) of 12-4-12 decreased between 0.2 and 0.8 wt% and then increased at 1 wt%. The increased cmc may be due to the formation of mixed micelles. For (inorganic additive) NaBr, cmc decreased continuously as a function of c(NaBr). Other parameters calculated include those related to the adsorption of the surfactant at solution/air interface, micelle aggregation number, and hydrodynamic radius. ILs behave as electrolyte and cosurfactants based on c(IL).

Surface-active properties of new cationic gemini surfactants with cyclic spacer

ABSTRACTThree cationic gemini surface active compounds of the type (1r,4r)-1,4-dialkyl-1,4-dimethy-l-piperazine-1,4-diium bromide (Ia, Ib, and Ic), were synthesized. They were characterized using elemental analysis and 1H-NMR spectra. Their surface-active properties were measured in aqueous solutions with different concentrations at different temperatures (25, 40, and 55°C). Various surface measurements of these gemini surfactants, (compared to the conventional one, 1-Dodecyl-1-methylpiperidinium bromide (a)) were estimated, specifically critical micelle concentration (CMC), effectiveness (πCMC), efficiency (PC20) as well as maximum surface excess (Γmax) and minimum surface area (Amin). The measurements of the gemini compounds gave low CMC, high efficiency in reducing the surface tension, and intense adsorption at air/water interface. These surfactants have lower Krafft points and thus better solubility. Thermodynamic data, free energy, entropy, and enthalpy changes (ΔG°, ΔS°, and ΔH°) for micellization at the air/water interface and also for adsorption in the bulk of surface-active solutions were calculated.

Cationic gemini surfactants containing an O-substituted spacer and hydroxyethyl moiety in the polar heads: Self-assembly, biodegradability and aquatic toxicity

Micellization and some ecological properties of new cationic gemini surfactants with oxygen-substituted spacer and hydroxyethyl groups connected to the polar heads have been studied. The incorporation of a hydroxyethyl group in the polar head favors self-aggregation whereas the presence of the oxygen in the spacer increases critical micelle concentration. Surfactants investigated are not biodegradable due to their toxic effect on microorganisms responsible for biodegradation. Aquatic toxicity increases with the hydrophobic chain and decreases by increasing the hydrophilicity of spacer and polar heads. New gemini surfactants are less toxic to the aquatic environment than monomeric surfactants and non-oxygen-containing gemini surfactants.

Effect of Hydrophobicity of Tails and Hydrophilicity of Spacer Group of Cationic Gemini Surfactants on Solvation Dynamics and Rotational Relaxation of Coumarin 480 in Aqueous Micelles.

Solvation dynamics and rotational relaxation of coumarin 480 in aqueous micelles of cationic gemini surfactants with diethyl ether (EE) spacer group (m–EE–m) and tails with varying tail lengths (m = 12, 14, and 16) have been studied. Studies have been carried out by measuring UV–visible absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, 1H NMR spectroscopy, and dynamic light scattering. Effects of hydrocarbon tail length and hydrophilicity of spacer group on solvation dynamics and rotational relaxation processes at inner side of the Stern layer of micelles have been studied. With increasing hydrophobicity of tails of surfactants, water molecules in the Stern layer become progressively more rigid, resulting in a decrease in the rate of solvation process with slow solvation as a major component. With increasing hydrophilicity of the spacer group of gemini surfactant, the extent of free water molecules is decreased, thereby making the duration of the solvation process longer. Solvation times in the micelles of gemini surfactants with hydrophilic spacer are almost 4 times longer compared to those in the micelles of their conventional counterpart. Rotational relaxation time increases with increasing tail length of surfactant as a result of increasing microviscosity of micelles with fast relaxation as a major component. With increasing hydrophilicity of the spacer group, the anisotropy decay becomes slower due to the formation of more compact micelles. Rotational relaxation in gemini micelles is also slower compared to that in their conventional counterpart. The anisotropy decay is found to be biexponential with lateral diffusion of the probe along the surface of the micelle as a slow component. Rotational motion of micelle as a whole is a very slow process, and the motion becomes further slower with increasing size of the micelle. The time constants for wobbling motion and lateral diffusion of the probe become longer with increasing microviscosity of micelles.

Synthesis and Properties of a Novel Gemini Surfactant with Bis-piperidinium

Abstract A novel cationic Gemini surfactant with bis-piperidinium and benzene ring (C10-CGP) was synthesized by aniline, epichlorohydrin and 1-bromodecane in three steps. The structure of C10-CGP was characterized by mass spectroscopy (MS) and nuclear magnetic resonance (1H NMR). The critical micelle concentration (CMC) and the corresponding surface tension (γ CMC) of C10-CGP were measured from 298 K to 313 K and the thermodynamic parameters of the micellization were calculated. The results showed that the critical micelle concentration (CMC) and γCMC were 0.976 × 10−3 mol · L−1 and 28.93 mN · m−1 at 298 K, respectively. With the temperature increase, the CMC increased, the maximum surface adsorption capacity (Γ max) decreased, the γ CMC decreased and the minimum molecule area (A min) increased. The free energy of the system during the micelle formation was negative. When the Gemini surfactant was used as an asphalt emulsifier, C10-CGP exhibited good a emulsifying ability. C10-CGP is a slow-set asphalt emulsifier.

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.

Impact of organic polar solvents (DMSO and DMF) on the micellization and related behavior of an anionic (AOT), cationic (CEM2AB) and cationic gemini surfactant (16-5-16)

The impact of cosolvents like aquo-organic media has a great focus of discursion in the field of chemical, industrial and pharmaceutical processes along with amphiphilic materials. Detailed study of dimethylsulfoxide and N,N-dimethyl formamide on the self-assembly and the energetic of three surfactants, anionic dioctyl sodium sulfosuccinate (AOT), cationic cetyl ethylhydroxy dimethylammonium bromide (CEM2AB) and cationic gemini N,N′-cetyl-N,N,N′,N′-tetramethyl-N-N′-pentanediyl diammonium dibromide (16-5-16) is clearly described by conductometric, tensiometric, spectro photometric, fluorimetric and calorimetric techniques. All of the surfactants used have equivalent tails, although type and size of their head groups are different. The solvent-composition-dependent properties are identified, and their quantifications are elaborated. The micellization process is assessed in terms of different solvent parameters and zeta potential values are also attempted through dynamic light scattering method (DLS). The values of both critical micelle concentration (cmc) and degree of dissociation increase with increasing concentration of cosolvent. The effect of solvent on free energy contribution to micellization, tail transfer Gibbs free energy, Gibbs adsorption energy etc. was studied. The enthalpy of micellization is estimated directly with the help of microcalorimeter for the lower range of DMSO solution. For AOT in aqueous medium, endothermic plot is observed whereas the other plots are exothermic in nature. Some micellar interfacial parameters were also our study of interest. The careful design of these conjugates exhibits properties which help to serve our focus. All of these results which are demonstrated is a new kind of endeavor.

Architecting organo silica nanosheets for regenerable cost-effective organics adsorbents

Organo silica nanosheets (organo-SiNSs) debut as superior adsorbents on organics removal stage. The precursor ultrathin silica nanosheets (SiNSs) provided with large surface area, uniform lamellar structure and low layer charge comes from acid leaching of vermiculite (Vt). By decoration with different cationic gemini surfactants, 1,3-bis (hexadecyldimethylammonio)-2-hydroxypropane dichloride (BHHP) and bis-N,N,N-hexadecyldimethyl-p-phenylenediammonium dibromide (BHPD), organo-SiNSs could be successfully prepared and used as adsorbent for benzoic acid (BA). The surface and structure of the resultant organo-SiNSs are characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), elemental analysis (EA), thermogravimetric analysis (TG), electron microscopy (SEM and TEM) and surface areas analysis (BET). Enhanced adsorption process detected by BA yields good potential from the standpoint of particularly rapid adsorption feature within 10min and cost-effective character throughout the process. The adsorption capacity of organo-SiNSs is much higher than the level of organo-clays. Intriguingly, the adsorption capacity of BHPD-SiNSs (81.72mgg−1) higher than that of BHHP-SiNSs (58.44mgg−1), which verifies the strength: π-π interaction>hydrogen bond. Kinetics, isotherm and thermodynamics analysis on the adsorption properties are also conducted for adsorption mechanisms. The adsorption process is sustainable as the spent organo-SiNSs could regenerate by simple acid pickling methods at least for three cycles. This adsorbent organo-SiNSs lifts the veil the enormous related organo-silicate materials to serve as tunable and cost-effective adsorbents for specific organics retention.

Density, dynamic viscosity, and kinematic viscosity studies of aqueous solution of a cationic gemini surfactant, hexanediyl-1,6-bis(dimethylcetylammonium bromide (16-6-16): Influence of electrolytes and temperature

In the present paper, we report density, dynamic viscosity and kinematic viscosity of a cationic gemini surfactant, hexanediyl-1,6-bis(dimethylcetylammonium bromide (16-6-16) aqueous solution in absence and presence of electrolytes at the temperature range from 393 to 343K. With increasing the temperature the density, dynamic viscosity and the kinematic viscosity of the pure gemini surfactant is decreasing; while increasing the concentration of gemini surfactant, 16-6-16 the values are increasing. In presence of electrolyte, an increasing trend was observed. However, with increasing the temperature (in presence of electrolyte), a similar decreasing trend was observed. The influence of metallic ion (co-ions) was found to be in the order: Li+<Na+<K+≅NH4+; whereas the influence of halide ion (counter ion) was found to be in the order: F−<Cl−<Br−<I−.

Mobilization and displacement of heavy oil by cationic microemulsions in different sandstone formations

Herein is presented a hybrid production scheme that considered the injection of gel type-microemulsions to mobilize and to displace stranded heavy oil. The present work investigated not only the flow of proposed microemulsions during their journey through the sandstone cores, but also evaluates the influence of flooding conditions on their displacement efficiency. The proposed microemulsion formulations were prepared from micellar slugs, which were found efficient in solubilizing for heavy oils especially when they were prepared from a cationic Gemini surfactant with a longer alkyl chain. A series of coreflood tests showed that the injection of formulated microemulsions in a conventional water-flooded Berea sandstones recovered about 20.3 and 31.6% of initial-oil-in place (IOIP). The same formulations, injected in an artificially fractured and heterogeneous sandstones, yielded an oil recovery of 6.4 and 8.4% of IOIP respectively. Regardless the nature of the network of oil-bearing matrix, the heaviest formulation, that was the microemulsion prepared from the cationic Gemini surfactant with the longest alkyl chain, stood as a better displacing agent compared to its counterpart prepared from the a short alkyl chain. The mechanism of oil production was found subsequent to a reduction in viscous forces (order of 10−10), which itself was altered by the chemistry inherent to the propagation of microemulsion and that of the formation brines. These concomitant mechanisms prompt the wettability alteration of the sandstone from mixed-wet to water-wet for conventional sandstone and to strongly-water unconventional cores. Also, the formation of sludgy materials, subsequent to microemulsion flooding, was drawn as the main challenge in this work that could be mitigated by altering the composition of the preflush stage. For this production to be efficient in an unconventional formation, the results presented herein suggest a modification of the injection scheme.

Coacervate of Polyacrylamide and Cationic Gemini Surfactant for the Extraction of Methyl Orange from Aqueous Solution.

Coacervation in aqueous solution of the mixture of cationic ammonium surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and 10% hydrolyzed polyacrylamide (PAM) has been investigated. It was found that the 12-6-12/PAM mixture forms coacervate with a large network structure over a wide concentration range of surfactant and polyelectrolyte and shows great efficiency in the extraction of Methyl Orange (MO) from water owing to the cooperation of hydrophobic, electrostatic, and π-cation interactions. Meanwhile, the dye joins the coacervate and strengthens the network structure of the coacervate. In particular, benefiting from partial excess of 12-6-12 molecules, the coacervate phase presents selective adsorption behavior toward anionic dye MO in the presence of cationic dye methylene blue (MB). Furthermore, the coacervate phase is utilized to modify quartz sand and melamine foam, and the coacervate-treated adsorbents can adsorb MO efficiently. Moreover, the MO-loaded adsorbents are easily regenerated with hydrochloric acid, making this an inexpensive and environmentally benign process. These findings offer a simple and effective alternative for the treatment of dye contaminated water and the recovery of dyes.

Benzene ring containing cationic gemini surfactants: Synthesis, surface properties and antibacterial activity

New quaternary ammonium gemini surfactants of the general formula CnH2n+1-Ph-NHCOCH2N+(CH3)2-(CH2)s-N+(CH3)2CH2CONH-Ph-CnH2n+1 (with n=8, 10, 12, 14, 16 and s=2, 4, 6) have been synthesized by an efficient synthetic pathway based on the quaternization of N,N,N′,N′-tetramethylalkylenediamine with 2-bromo-N-(4-(alkyloxy) phenyl) acetamides. Their surface properties were investigated by surface tension, electrical conductivity and dynamic light scattering (DLS) measurements. The study shows that the incorporation of a benzene ring in the hydrophobic tail prompts micelle formation which leads to a smaller cmc values in the range of 0.21–0.009mM compared to analogous geminis bearing alkyl hydrophobic chains. The length of the spacer and the hydrophobic chain has a pronounced effect on the aggregation behavior of surfactants molecules. This was confirmed by the average surfaces occupied by these molecules at the water–air interface calculated from the Gibbs equation. The size of the aggregates was measured by employing dynamic light scattering technique. The antimicrobial activity of investigated surfactants was evaluated against three microorganisms: Staphylococcus aureus, Escherichia coli and Candida albicans.