Counterion Binding Research Articles

Micellization and gelation characteristics of Pluronic P123 and single ester-bonded cleavable cationic gemini surfactant: A potential system for solubilization and release of ibuprofen

We herein report the mixed micelle and monolayer formation of mixtures of a biocompatible and cleavable oxy-diester twin tailed (gemini) surfactant, 2,2′-[(oxybis(ethane-1,2-diyl))bis(oxy)]bis(N-hexadecyl-N,Ndimethyl-2-oxoethanaminium) dichloride (16-E1-16) with the triblock copolymer, P123 (HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H) using tensiometry, dynamic light scattering (DLS), and rheology. It was observed that P123 and 16-E1-16 have strong interaction and form small mixed micelles with similar micellar composition throughout the bulk mole fraction range with insignificant counterion binding. Besides, P123 and 16-E1-16 mixed surfactant system forms thermodynamically stable mixed monolayer that is rich in P123. Variation of viscosity with shear rate revealed better injectable property of the formulations of binary mixtures of P123 and 16-E1-16 compared to pure P123. Also, below α16-E1-16 = 0.3, all the mixtures were in the form of sol which transform into a weak gel at physiological temperatures making these formulations relevant as injectable delivery system. Solubilization capacity of these mixed micelles towards ibuprofen (IBU) showed that addition of 16-E1-16 to P123 micelles reduces its solubilization capacity but with the advantage of making the formulation injectable due to their favorable shear induced viscosity changes and thermogelation properties. Mixed micelles showed faster drug release rate predominantly following Fickian mechanism with negligible contribution of relaxation process in the release phenomena. There is no report showing interaction of biocompatible and cleavable gemini surfactant 16-E1-16 with P123 in mixed micelle and monolayer formation with detailed rheological, drug encapsulation and release studies even though this amphiphilic system has a potential to act as an injectable drug delivery system.

The physicochemical variables and interaction forces for the association of dodecyltrimethylammonium bromide + cefixime trihydrate mixture in aq. short chain alcohols and urea media at different temperatures

To develop the drug formulation and reduce antibiotic resistance in the human body, it is essential to study the drug-surfactant interaction. Herein, the interactions between cefixime trihydrate (CMT) and dodecyltrimethylammonium bromide (DTAB) have been evaluated in different experimental situations at a certain range of temperature (300.55–320.55 K) by means of conductivity measurement. The micellar parameters (CMC, degree of counter ion binding (β)) along with some thermodynamic variables like ΔGm0, ΔHm0, and ΔSm0 etc. were evaluated to investigate the interactions between CMT and DTAB. The plot of specific conductivity against surfactant concentration of the DTAB + CMT mixed system was used to determine critical micelle concentration (CMC). The increase of concentration of alcohols (ethanol and 1-propanol) and urea lowers the counterion binding and enhance the CMC values of the DTAB + CMT system. The increase in temperature causes delayed micellization of DTAB + CMT mixture both in aq. alcoholic and urea media. The alteration of CMC values of the DTAB + CMT implies the existence of interaction between DTAB and CMT in the study environment. The micellization of the DTAB + CMT mixed system in all experimental conditions investigated is spontaneous process that has been confirmed by the achieved negative values of ΔGm0. The values of ΔHm0 and ΔSm0 expose the presence of hydrophobic and electrostatic interactions between CMT and DTAB while the contribution of electrostatic interaction is the main force in aq. EtOH medium.

Examination of mixed sodium dodecyl sulfate – 1-butanol micelles with molecular dynamics

Properties of mixed micelles composed of sodium n-dodecyl sulfate surfactant and 1-butanol co‑surfactant were examined using molecular dynamics simulation for three experimentally observed compositions. The aggregation number varied in the range of 30 to 64, and the co-surfactant content was 75 to 32 molecules, respectively. The composition of the bulk water – 1-butanol mixture matched the experimentally studied concentrations. All-atom potential models and explicit solvent were used in order to capture the most structural details. Such characteristics as micelle size, co-surfactant location, depth of water penetration were determined. The simulated micelles were found to have compact ellipsoidal shape, except of the most co-surfactant-rich ones, which were elongated. The equilibrium composition differed little from the initial one indicating consistence of the simulations. The co-surfactant molecules were observed in different positions: either situated on the surface of surfactant aggregate or having hydrocarbon tails immersed in it. Still, the hydroxyl groups stayed on the micelle surface and preserved contact with bulk solution. Water molecules were found penetrating the mixed micelles up to 0.3 – 1.0 nm from their center. Degree of counterion binding was estimated and its dependence on micelle composition was derived. It was found to decrease with the co-surfactant content in a non-linear manner. Specifically, for co-surfactant content up to 34% the counterion binding was almost similar to that of pure sodium n‑dodecyl sulfate micelles; the value gradually fade at higher 1-butanol content. Several positions of the boundary between bound and free counterions were considered. The approach proposed here may be employed for examination of other mixed micelles, as well.

Ion-pairing equilibria and kinetics of dimethyl phosphate: A model for counter-ion binding to the phosphate backbone of nucleic acids

Dimethyl phosphate (DMP–) is the simplest model ion to assess ion-pairing phenomena between metal ions and the phosphate backbone of nucleic acids. Yet, the equilibria and dynamics of ion binding to DMP– have not been fully uncovered. Here, we study the interaction of DMP– with different cations and water in aqueous solutions of NaDMP using dielectric relaxation and nuclear magnetic resonance spectroscopies. We find DMP– to be weakly hydrated and weakly associated with Na+ in the absence of added salt. Upon addition of NaCl, MgCl2, or CaCl2 to solutions of NaDMP, we detect the formation of solvent-shared (NaDMP0) and contact (MgDMP+, CaDMP+) ion-pairs; the degree of ion association is 20–27 % at 2:1 salt:DMP molar ratio for the bivalent ions. Comparison to literature results suggests the formation constant of MgDMP+ to be a good estimate for the binding of Mg2+ to RNA. From the concentration dependence of the rotational relaxation time of the ion-pairs, we find ion-pair dissociation rates to follow the order Mg2+≪Ca2+<Na+. Strikingly, our data suggest that the overall ion-pair dissociation dynamics are governed by an ion-pair metathesis reaction, which provides a different pathway for the binding of ions by DMP–.

Synthesis and properties of sodium carboxylate silicone surfactant via thiol-ene “click” reaction

The sodium carboxylate silicone surfactant (Si4-COONa)was synthesized via thiol-ene “click” reaction. Its chemical structure was confirmed by 1H NMR, and ESI-MS. The surface activity and aggregation behavior in aqueous solution were investigated by electrical conductivity, surface tension, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Si4-COONa exhibited admirable surface activity and could reduce the water's surface tension to 19.4 mN·m−1. The electrical conductivity showed that the counterion binding value of Si4-COONa increases with increasing temperature. By analyzing the thermodynamic parameters of micellization, it was found that the micellization of Si4-COONa is spontaneous and entropy driven. The addition of inorganic and organic salts in the aqueous solution decreases the critical micelle concentration remarkably. The TEM and DLS results indicated that the Si4-COONa in aqueous solution or salts solution formed spherical aggregates above the critical micelle concentration.

The impact of sodium salts on the physicochemical properties of the mixture of tetradecyltrimethylammonium bromide and metformin hydrochloride drug at several temperatures

Metformin hydrochloride (MNH) is recommended for diabetics. In the current investigation, assembly behaviour of the tetradecyltrimethylammonium bromide (TTAB) + MNH mixture in different Na-salts media has been carried out over 298.15–323.15 K using a conductometric tool to insight the interaction between MNH and TTAB. The extent of interaction was measured from the different parameters associated with micellization. The critical micelle concentration (CMC) of TTAB + MNH was achieved to be lower in the electrolyte medium. The CMC values were found to be augmented with the boost in temperature. The degree of counterion binding (β) experienced to be reduced with the elevation of temperature. The values of free energy of micellization were negative in all studied media which reveals spontaneous micellization. Enthalpy of micellization was negative (except Na2SO4) at all temperatures which signify exothermic assembly phenomenon (endothermic in Na2SO4). The values of and entropy of micellization reveal the presence of both electrostatic and hydrophobic interaction as key forces amongst the components examined. The different thermodynamic parameters of transfer and enthalpy–entropy compensation variables were also estimated and explained with suitable judgment.

Effect of drug aceclofenac on physicochemical properties of mixed micellar systems

In this article, the effect of the drug aceclofenac (ACF) on the properties of three mixed micellar systems are studied. The three systems were pluronic L64 + F127 (nonionic-nonionic), pluronic L64 + CTAB (cetyltrimethyl ammonium bromide), (nonionic-cationic) and L64 + SDS (Sodium dodecyl sulphate), (nonionic-anionic) combinations. The physicochemical parameters were characterized by different techniques such as UV visible spectroscopy, FTIR, conductance, DLS, and SEM. The presence of ACF affected the nonionic-ionic mixed micelles more than the nonionic-nonionic group as evidenced by UV spectroscopy. From the DLS measurement, it was observed that ACF enhanced the size of the single micelle of pluronic L64 from 98 to 168 nm. The size of the cationic mixed micelle with ACF displayed 329 nm and the anionic mixed one showed 291 nm suggesting enhanced entrapment efficiency of their mixed micelle compared to the single micelles. The size was also reconfirmed by SEM analysis. From the conductivity measurements of the two nonionic-ionic micellar systems, the counter ion binding constant β, and the thermodynamic parameters ΔG, ΔH, and ΔS were determined. The negative value of ΔG infers spontaneous binding between ACF and ionic mixed micelles.Article highlightsIonic mixed micelles are more effective than nonionic pair.ACF has more spontaneous binding with anionic mixed micelle compared to cationic.The drug entrapment efficiency is better in mixed micelles than in single micelles.

Studies on Intermolecular Interaction of N-Glycidyltrimethyl Ammonium Chloride Modified Chitosan/N,N-Dimethyl-N-dodecyl-N-(2,3-epoxy propyl) Ammonium Chloride and Curcumin Delivery.

Chitosan has potential applications in many fields, due to its biocompatibility, biodegradability and reproducibility. However, the insolubility in water restricts its wide application. In order to expand the application of chitosan in the delivery of oil-soluble drugs and improve the efficacy of oil-soluble drugs, N-Glycidyltrimethyl ammonium chloride-modified chitosan (GTA-m-CS) and N,N-Dimethyl-N-dodecyl-N-(1,2-epoxy propyl) ammonium chloride (DDEAC), a kind of reactive surfactant, were synthesized and characterized by FTIR, NMR and XRD methods. The interactions between GTA-m-CS and DDEAC was studied by surface tension, viscosity, conductivity and fluorescence methods. The parameters, including equilibrium surface tension, critical micelle concentrations of DDEAC with different GTA-m-CS concentration, critical aggregation concentration of DDEAC, the amount of DDEAC adsorbed on GTA-m-CS, pc20 and πcmc were obtained from the surface tension curves. The influence of temperature on the above parameters were evaluated. The degree of counterion binding to micelle and the thermodynamic parameters of the system were calculated from the conductivity curves. According to the change of conductivity with temperature, the thermodynamic parameters of micellar formation were calculated. The aggregation number of DDEAC molecules in GTA-m-CS/DDEAC aggregates were calculated from steady-state fluorescence data. Based on the experimental results, the interaction models between GTA-m-CS and DDEAC were proposed. The GTA-m-CS/DDEAC aggregates could be used as curcumin carries, and achieved sustained release.

Counterion-Induced Aggregation of Metallacarboranes

The model of counterion-induced metallacarborane aggregation in water was verified on sodium bis(1,2-dicarbollide), one of the most studied examples of metallacarboranes. This case study introduces a novel approach in anionic boron cluster self-assembly that resembles the behavior of polyoxometalate nanoions. The key prerequisite of the counterion binding to the aggregates is the strongly uneven charge distribution of cobalt bis(dicarbollide) clusters. Simultaneously, the size of the counterion should fit into the void between the metallacarborane clusters within the aggregate. In consequence, compact pentamers with two bound sodium cations via Coulombic-driven assembly are formed. This behavior cannot be explained solely by the hydrophobic effect─the paradigm of metallacarborane aggregation in the current literature. The pentamers can merge into bigger nanostructures via the second aggregation mechanism that sheds light on the complex behavior of metallacarboranes in water. The proof-of-concept of counterion-induced metallacarborane aggregation and the proposed total description of the self-assembly via the two-process model are results of calorimetry modeling, quantum chemistry calculations, and molecular dynamics simulations.

The effect of explicit counterion binding on the transference number of polyelectrolyte solutions.

Polyelectrolyte solutions have been proposed as a method to improve the efficiency of lithium-ion batteries by increasing the cation transference number because the polymer self-diffusion coefficient is much lower than that of the counterion. However, this is not necessarily true for the polymer mobility. In some cases, negative transference numbers have been reported, which implies that the lithium ions are transporting to the same electrode as the anion, behavior that is often attributed to a binding of counterions to the polyion. We use a simple model where we bind some counterions to the polymer via harmonic springs to investigate this phenomenon. We find that both the number of bound counterions and the strength of their binding alter the transference number, and, in some cases, the transference number is negative. We also investigate how the transference number depends on the Manning parameter, the ratio of the Bjerrum length to charge separation along the chain. By altering the Manning parameter, the transference number can almost be doubled, which suggests that charge spacing could be a way to increase the transference number of polyelectrolyte solutions.

Condition dependent self-aggregation behavior of aerosol-OT in mixed water-alcohol media: Physicochemical investigation

Amphiphiles aggregation in mixed aquo-organic solvent media has profound interest in the fields of chemistry, biology, pharmaceutics, and industry. Detailed fundamental understanding of the process in the bulk and at the interface is still remaining to be explored. In this report, the effect of two water miscible alkanols (ethanol (ET), and isopropanol (IP)) on the aggregation-behaviors of the surfactant sodium dioctylsulfosuccinate (Aerosol-OT or AOT) has been studied in a wide range of alcohol proportions (0 to 100 vol%) in water. Different physicochemical parameters like critical micelle concentration (CMC), counter-ion binding (β) and aggregation number (Nagg) of micelles, and the energetics of the AOT adsorption at the air/water interface, and its assembly formation in the bulk have been evaluated employing tensiometry and isothermal titration calorimetry (ITC) methods. The micelle forming region of AOT has been found to be 0–30 vol% for ET, and 0–20 vol% for IP. At [solvent] > 30 vol% the possibility of formation of “randomly arranged globular assembly” (RAGA) of the amphiphile [1] prevailed. Role of different solvent parameters have been attempted to explain the thermodynamics of the micellization process of AOT. SANS experiments have supported vesicle formation of concentrated solutions of AOT in 50 vol% ET or IP in water; with increasing alcohol vesicles transformed into micelles. DFT (density functional theory) calculations have been made for understanding the intermolecular interactions in AOT-H2O-ET or IP systems compared to their binary mixtures (AOT-H2O; AOT-ET; AOT-IP). NMR study has supported favorable interactions of the alkanols (ET and IP) with the head group of the AOT. Formation of micelles and reverse micelles by AOT in different composition of alcohols and pure alcohols reported by Michor and Berg [2] has been reasoned out to be incorrect.

Influences of NaCl and Na2SO4 on the Micellization Behavior of the Mixture of Cetylpyridinium Chloride + Polyvinyl Pyrrolidone at Several Temperatures.

Herein, the conductivity measurement technique is used to determine the interactions that may occur between polyvinyl pyrrolidone (PVP) polymer and cetylpyridinium chloride (CPC) surfactant in the presence of NaCl and Na2SO4 of fixed concentration at variable temperatures (298.15–323.15 K) with an interval of 5 K. In the absence or presence of salts, we observed three critical micelle concentrations (CMC) for the CPC + PVP mixture. In all situations, CMC1 values of CPC + PVP system were found to be higher in water than in attendance of salts (NaCl and Na2SO4). Temperature and additives have the tendency to affect counterion binding values. Various physico-chemical parameters were analyzed and demonstrated smoothly, including free energy (ΔG0m), enthalpy (ΔH0m) and entropy change (ΔS0m). The micellization process is achieved to be spontaneous based on the obtained negative ΔG0m values. The linearity of the and values is excellent. The intrinsic enthalpy gain (ΔH0*m) and compensation temperature (Tc) were calculated and discussed with logical points. Interactions of polymer hydrophobic chains or the polymer + surfactant associated with amphiphilic surface-active drugs can employ a strong impact on the behavior of the gels.

Ionic effects on supramolecular hosts: solvation and counter-ion binding in polar media.

For the progress of synthetic supramolecular chemistry in aqueous solution the design of host molecules soluble in this medium is essential. A possible route is the introduction of ionic residues, with the additional advantage that also electrostatic interactions can be used to form supramolecular architectures. In this work we study the effect of different ionic substituents on a resorcin[4]arene host on solvation and counterion binding in water and dimethyl sulfoxide (DMSO). To do so, we combine dielectric relaxation spectroscopy (DRS) at 298.15 K and dilute-solution conductivity measurements covering 278.15-308.15 K. The results indicate that studied substituents lead to a comparable increase in solubility in both water and the dipolar-aprotic DMSO. However, solvation and counterion binding not only depend on the nature of the ionic substituent but also on the solvent. Although intrinsically hydrophobic in nature, resorcin[4]arenes with ionic substituents also show strong hydrophilic hydration in water, with the extent depending on the nature of the ionic group. In contrast to that, solvophobicity apparently dominates the interactions of DMSO with the solute. Counterion binding was found for both solvents and is essentially determined by solvent polarity. It appears that, compared to neat DMSO, the solubility of the cationic resorcin[4]arene with dimethylamine substituents is strongly increased in water-DMSO mixtures due to the formation of hydrogen bonds between two DMSO molecules and one water molecule.

Effects of Selected Metal Chlorides on the Micellization Parameters of Cetrimonium Bromide at Different Temperatures

The pre-modification of surfactant counterions using transition metal salts provides a means to activate the interface using corresponding properties of metal ions. In this work, a cationic surfactant cetyltrimethylammonium bromide (CTAB) was modified by pre-mixing metal chlorides (FeCl3, CuCl2 and ZnCl2) and CTAB in 1:1 molar ratio using methanol as solvent. As a result, FeCl3, CuCl2 and ZnCl2 were added as [FeCl3Br]-1, [CuCl2Br]-1 and [ZnCl2Br]-1 respectively acting as counter anions (CAs) instead of bromide anion. Hence CTAB was called CTAF, CTAC and CTAZ in order of added CAs i.e., [FeCl3Br]-1, [CuCl2Br]-1 and [ZnCl2Br]-1 respectively. The effect of these metal chlorides on the micellar behaviour of CTAB was investigated using conductivities of their different solutions. Furthermore, the critical micelle concentration (CMC) as well as the degree of counterion binding were considered at 25.0, 30.0, 35.0, 40.0 and 45.0 and#176;C 0.1 and#176;C. The analysis of results revealed that incorporation of metal cations reduces the CMC values in the order CTAF CTAZ CTAC CTAB. Change in entropy (S), enthalpy (H) and free energy (G) were calculated to understand the thermodynamics of micellization under the circumstances. The aim of this study is to improve the understanding regarding the presence of transition metals in micellization process as well as the possibility of their interactions with Bromide counterions and possibility of the formation of complex counter-anions.

Osmotic Pressure and Diffusion of Ions in Charged Nanopores.

The transport of ions and water in nanopores is of interest for a number of natural and technological processes. Due to their practically identical long straight cylindrical pores, nanoporous track-etched membranes are suitable materials for investigation of its mechanisms. This communication reports on simultaneous measurements of osmotic pressure and salt diffusion with a 24 nm pore track-etched membrane. Due to the use of dilute electrolyte solutions (1–4 mM KCl and LiCl), this pore size was commensurate with the Debye screening length. Advanced interpretation of experimental results using a full version of the space-charge model has revealed that osmotic pressure and salt diffusion can be quantitatively correlated with electrostatic interactions of ions with charged nanopore walls. The surface-charge density is shown to increase with electrolyte concentration in agreement with the mechanism of deprotonation of weakly acidic surface groups. Moreover, a lack of significant surface-charge dependence on the kind of cation (K+ or Li+) demonstrates that binding of salt counterions does not play a major role in this system.

Utilization of amphiphilic antihistamines drugs to enhance micellization of anionic surfactant and improve the binding and solubility of Itraconazole drug

Many salt-based medicines are used in pharmaceutical formulations as active components. Excipients performance can be improved by using these medicines. The use of amphiphilic antihistamine medications (diphenhydramine hydrochloride (DPC) and cetirizine hydrochloride (CTZ)) to improve sodium dodecylbenzene sulfonate (SDBS) micellization is demonstrated in this work. DPC/CTZ considerably lowered the critical micelle concentration (CMC) of SDBS in aqueous media by measuring conductivity. SDBS micelles demonstrated a greater electrostatic interaction with CTZ than DPC micelles, based on counterion binding (βc and B) and binding constant (Kb) values. The DPC/CTZ mean ion occupancy (i0) per SDBS micelle was also calculated using the UV spectroscopy experiment. For SDBS micelles, we observed that DPC and CTZ had i0 values of 1.700 and 2.622, respectively. The electrostatic interaction between the medication and the surfactants was shown to be controlling the i0 levels. The medicine Itraconazole (ITZ), which is poorly water-soluble, was found to be more soluble in SDBS micelles containing CTZ than in DPC combinations. At 0.002 mol L-1 in the aqueous medium, the greatest i0 values of ITZ were 185 in SDBS + DPC and 203 in SDBS + CTZ. The CMC and the binding behaviour of drug-micelles were found to be critical determinants in controlling ITZ drug solubilization. Finally, we concluded that the above formulation might be used in the pharmaceutical industry to improve multi-drug delivery systems.

Exploring the effects of selected essential amino acids on the self-association of sodium dodecyl sulphate at different temperatures

Sodium dodecyl sulphate (SDS) has well established biological applications in the determination of molecular weights and structure determination of proteins, peptides etc. Due to these reasons, the study of SDS interactions with essential amino acids (AAs) can be valuable as they can diversify the use of SDS in applications of importance in biology and drug delivery designs etc. The aggregation process of SDS and its detailed physiochemical properties in aqueous system, in the presence and absence of three essential amino acids L-Threonine (THR), DL- Methionine (MET) and L-Phenylalanine (PHE), is studied in a temperature range of 293 K-323 K using conductivities, surface tension (γ), particle size and zetapotential measurements using dynamic light scattering (DLS) technique. From conductivity measurements, critical micelle concentration (CMC), counterion binding (β) and thermodynamic parameters such as standard free energy change of micellization (ΔGmo), standard enthalpy change of micellization (ΔHmo), standard entropy change of micellization (ΔSmo) etc., are calculated. The surface properties and interfacial parameters of SDS systems are studied using surface tensiometery. Results established that the presence of amino acids (AAs) reduced the CMC of SDS. The electrostatic interaction of AAs with charged micellar surface were also observed. The micellization process of SDS was found thermodynamically feasible in the aqueous amino acid (AAA) system. From the surface tension data, interfacial parameters such as Гmax, Amin,pC20 , and surface effectiveness of SDS in aqueous and AAA system have been calculated and compared. It was revealed that surface adsorption and rearrangement of SDS molecular ion at their micellar concentration at air/liquid interface are significantly affected by AA addition. Hydrodynamic diameter (Dh) and zetapotential (ζ) of aqueous SDS solution helped to check the effect of amino acid additives on the colloidal size and stability of SDS aggregates. The results from different techniques were consistent to establish the feasibility of SDS micellization process in aqueous as well as aqueous AA solution.

Impact of ethanol and NaCl on the acid yellow dye mediated self-aggregation of sodium dodecyl sulfate: A combined investigation by conductivity and molecular dynamics simulation

Herein, we report the micellization behavior of the mixture of sodium dodecyl sulfate (SDS), and acid yellow (AY) dye in water, water + ethanol, and water + NaCl media. The degree of interaction between SDS and AY has been assessed quantitatively from the estimated values of critical micelle concentration (cmc). Three cmc values were observed for the AY + SDS systems at each temperature and solvents utilized, which exhibit a reversed U-shaped variation with respect to the change of temperature in aqueous/NaCl solution while increased monotonically in ethanolic medium almost in all cases. The extent of micellization was found to be disfavored in presence of AY dye. The micellization was also found to be disfavored up to 15% ethanol and favored in the addition of electrolyte species. The values of counterion binding were found to be temperature dependent. The Gibbs free energy (ΔGmo), which was found negative, reveal a spontaneous micellization of AY + SDS system. The other thermodynamic parameters, like enthalpy (ΔHmo) and entropy (ΔSmo) of micellization along with different transfer energies, were also assessed to have an insight on the mode of interaction of surfactant and dye assemblies. The molecular level interaction between SDS and AY has been unveiled by Molecular Dynamics (MD) simulation and exhibits good agreement with experimental results.

Synthesis, aggregation, and biocidal properties of N-2-hydroxypropyl piperidine based cationic surfactants

New cationic ionic liquid surfactants (ILS) based on (C9-C10, C12 and C14) alkyl bromides and N-2-hydroxypropyl piperidine have been synthesized. Colloidal parameters of aqueous solutions of the obtained ILSs were studied by surface tension and dynamic light scattering methods. Specific electrical conductivity was measured by the conductometric method. Depending on the alkyl chain length, critical micelle concentration (CMC), maximum adsorption (Гmax), the minimum cross-sectional area of the surfactant polar group (Amin), adsorption efficiency (pC20), surface pressure (πCMC), degree of counterion binding (β), changes of the Gibbs free energy of micellization and adsorption (ΔGmic and ΔGad) were studied. The ILSs antimicrobial properties were tested on various bacteria and fungi.

Interaction of crystal violet dye with dodecyltrimethylammonium bromide in aqueous and electrolyte medium at different temperatures

Dyeing is one of the most important processes in the textile industries which require optimum binding of dye with the fabrics. In the binding phenomenon of dye with the fabrics, surfactants play a significant role. The presence of different auxiliaries modifies the dye-surfactant interaction which can influence the binding of dye with the fabrics. Herein, we studied the interaction of crystal violet (CV) dye with a cationic surfactant, dodecyltrimethylammonium bromide (DTAB) conductometrically in absence and presence of electrolytes (NaBr, Na2SO4, and Na3PO4). The critical micelle concentration (cmc) of DTAB was found to dwindle with the boost of concentration of CV. The cmc of CV + DTAB mixtures were monotonically increased with the increase of temperature. The presence of electrolytes facilitates the micellization of CV + DTAB mixture. The values of counterion binding were found to be augmented with the augmentation of temperature in aqueous and NaBr media while the opposite trend was observed in Na2SO4 and Na3PO4 media. The Gibbs free energy of micellization (ΔGm0) were found to be negative in all cases. The enthalpy (ΔHm0) and entropy (ΔSm0) of micellization were negative and positive in aqueous, NaBr, and Na2SO4 media while both values were positive in Na3PO4 medium. The enthalpy–entropy compensation parameters suggest that the most stable micelle of CV + DTAB is formed in Na2SO4 medium.