Synthesis and surface properties of chemodegradable anionic surfactants: Sodium salts of sulfated 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes

In acid-catalyzed reactions of long-chain aliphatic aldehydes (Ia-d) (a,R=n-C₅H₁₁; b,R=n-C₇H₁₅; c,R=n-C₉H₁₉; d,R=n-C₁₁H₂₃) with 1,1,1-tris(hydroxymethyl)-ethane (II), 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes (IIIa-d) were obtained. Then they were reacted with SO₃·pyridine complex in dry carbon tetrachloride solution, to obtain trisubstituted derivatives of 1,3-dioxane (IVa-d). They constitute a new group of chemodegradable, acetal-type anionic surfactants, which may readily hydrolyze and oxidize to nonsurfactant compounds. Physical data of the new compounds and some surface properties, such as Krafft point, critical micelle concentration (CMC), surface tension of aqueous solution near CMC (γ_CMC) and wetting and foaming properties, were determined. Sodium salts of sulfated 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes (IVa-d) exhibit aqueous solution properties similar to those of the well-known sodium alkyloligooxyethylene sulfates. Presence of the 5-methyl-1,3-dioxane moiety in molecules of compounds IVa-d introduces hydrophobic character comparable to the effect of three oxyethylene groups (-CH₂CH₂O-) or of two methylene groups (-CH₂-) of the alkyl chain in sodium alkyl ether sulfates [R(OCH₂CH₂)_mOSO₃Na] with equal R value. Part XXV in the series: Chemical Structure and Surface Activity. Part XXIV: A. Sokołowski, B. Burczyk, H.-R. Holzbauer, M. Herbst,Colloids Surfaces 57: 307 (1991).     

Synthesis and surface properties of chemodegradable anionic surfactants: Sodium carboxylates of cis-1,3-dioxane derivatives

The 2-n-alkyl-5-carboxy-5-methyl-1,3-dioxanes were obtained in good yield from the reaction of aliphatic aldehydes with 2,2-bis(hydroxymethyl)propionic acid in dichloromethane solution, catalyzed by p-toluenesulfonic acid monohydrate. Nuclear magnetic resonance analysis indicated that they were pure cis-isomers with the axial configuration of the carboxylic group at the C-5 carbon atom of the 1,3-dioxane ring. The acids were converted, with retention of the configuration, to their sodium salts by reaction with sodium methoxide or sodium hydroxide in methanol. The physicochemical properties of the acids and sodium salts, as well as their surface properties at the aqueous solution-air interface, were determined. Critical micelle concentration, surface excess concentration, surface area demand per molecule of sodium salts at the monomolecular surface layer, and standard free energy of micellization were determined based on surface tension measurements. Part XXXIV in the series: Chemical Structure and Surface Activity. Part XXXIII: A. Piasecki, A. Sokolowski, B. Burczyk, R. Gancarz, and U. Kotlewska, Synthesis, Surface Properties and Hydrolysis of Chemodegradable Anionic Surfactants: Diastereomerically Pure cis- and trans-2,5-Disubstituted-1,3-dioxanes. J. Colloid Interface Sci. 192:74–82 (1997).     

Preparation of a New Oligomeric Surfactant: N,N,N′,N″,N″-Pentamethyl Diethyleneamine—N,N″-Di-[Tetradecylammonium Bromide] and the Study of its Thermodynamic Properties

A new oligomeric surfactant: N,N,N′,N″,N″- pentamethyl diethyleneamine—N,N″-di-[tetradecylammonium bromide] referred to as 14-2-N(CH₃)-2-14 was synthesized, purified and characterized by Elemental Analysis, ¹H and ¹³C NMR and Electrospray. The micellar properties of this compound were determined by electrical conductivity and surface tension methods. Optical microscopy was also employed to study the behavior of anhydrous surfactant and the binary water/surfactant system as a function of temperature. The critical micellar concentration (cmc), degree of counterion binding and thermodynamic parameters of micellization (standard molar Gibbs energy, enthalpy and entropy of micellization) were determined by electrical conductivity measurements in the temperature range [24–54 °C]. Surface tension measurements also provide information about the dependence of the surface tension at the cmc (γ_cmc), pC₂₀ (negative logarithm of the surfactant’s molar concentration C₂₀, required to reduce the surface tension by 20 mN/m, the surface excess (Γ_max) at air/solution interface, the minimum area per surfactant molecule at the air/solution interface (Amin), surface pressure at the cmc (П_cmc), critical packing parameter(CPP) and the standard free energies of micellization ( \Updelta G_m⁰\Updelta G_{m}^{0}) and of adsorption ( \Updelta G_\textads⁰ \Updelta G_{\text{ads}}^{0} ).     

Synthesis and Surface-Active Properties of a Homologous Series of Star-Like Triple-Chain Anionic Surfactants Derived from 1,1,1-Tris(hydroxymethyl)ethane

A novel homologous series of trimeric anionic surfactants, 3C_nTE3CNa (where n is a fatty acid chain length of 7, 10, or 12), with three hydrocarbon chains and three carboxylate heads connected via tri‐etheric bonds were synthesized from long‐chain α‐bromo fatty acids and a triol, 1,1,1‐tris(hydroxymethyl)ethane. The obtained trimeric carboxylic acids were esterified and purified by silica gel column chromatography, then hydrolyzed with dilute sodium hydroxide solution to form a series of trimeric carboxylate surfactant products. All prepared compounds were analyzed by IR, ¹H NMR, and ¹³C NMR spectroscopy to confirm their chemical structures. Their surface‐active properties were investigated. The critical micelle concentrations (cmc) of 3C_nTE3CNa were in the range of 0.12–0.71 mmol/L, and the surface tensions at the cmc (γ_cmc) were 29.3–34.8 mN/m.     

Fatty acid metabolism in marine fish: Low activity of fatty acyl Δ5 desaturation in gilthead sea bream (Sparus aurata) cells

Marine fish have an absolute dietary requirement for C₂₀ and C₂₂ highly unsaturated fatty acids. Previous studies using cultured cell lines indicated that underlying this requirement in marine fish was either a deficiency in fatty acyl Δ5 desaturase or C_18–20 elongase activity. Recent research in turbot cells found low C_18–20 elongase but high Δ5 desaturase activity. In the present study, the fatty acid desaturase/elongase pathway was investigated in a cell line (SAF-1) from another carnivorous marine fish, sea bream. The metabolic conversions of a range of radiolabeled polyunsaturated fatty acids that comprised the direct substrates for Δ6 desaturase ([1-¹⁴C]18∶2n−6 and [1-¹⁴C]18∶3n−3), C_18–20 elongase ([U-¹⁴C]18∶4n−3), Δ5 desaturase ([1-¹⁴C]20∶3n−6 and [1-¹⁴C]20∶5n−3), and C_20–22 elongase ([1-¹⁴C]20∶4n−6 and [1-¹⁴C]20∶5n−3) were utilized. The results showed that fatty acyl Δ6 desaturase in SAF-1 cells was highly active and that C_18–20 elongase and C_20–22 elongase activities were substantial. A deficiency in the desaturation/elongation pathway was clearly identified at the level of the fatty acyl Δ5 desaturase, which was very low, particularly with 20∶4n−3 as substrate. In comparison, the apparent activities of Δ6 desaturase, C_18–20 elongase, and C_20–22 elongase were approximately 94-, 27-, and 16-fold greater than that for Δ5 desaturase toward their respective n−3 polyunsaturated fatty acid substrates. The evidence obtained in the SAF-1 cell line is consistent with the dietary requirement for C₂₀ and C₂₂ highly unsaturated fatty acids in the marine fish the sea bream, being primarily due to a deficiency in fatty acid Δ5 desaturase activity.     

Synthesis,surface active and thermal properties of novel imidazolium cationic monomeric surfactants

A series of long chain water soluble cationics have been synthesized by using renewable raw materials like fatty alcohols and epichlorohydrin. The surface activity of the molecules has been determined by measurement of their conductance and surface tension in aqueous solution. The dynamics of surface activity of these surfactants have also been investigated in the presence of sodium halides, NaCl and NaBr by surface tension measurement. A series of useful parameters like critical micelle concentration (cmc), surface tension at the cmc (γ_cmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (Π_cmc), Gibbs free energy of the micellization (ΔG_0 mic) and Gibbs free energy of adsorption (ΔG_0 ads) have been determined from the measurements obtained by surface tension and conductivity method. Further with the application of the Gibbs adsorption isotherm, maximum surface excess concentration (θ_max) and minimum surface area/molecule (A_min) at the air–water interface were also estimated. Thermal stability of these long chain cationics has been measured by thermal gravimetric analysis under nitrogen atmosphere. Analysis of thermal stability measurement indicated that the thermal stability of these long chain imidazoliums increase with an increase in chain length.     

Synthesis and surface properties of chemodegradable anionic surfactants: Diastereomeric (2-n-alkyl-1,3-dioxan-5-yl) sulfates with monovalent counter-ions

Sodium, potassium and ammonium cis- and trans-(2-n-alkyl-1,3-dioxan-5-yl) sulfates 6–8 (alkyl: n-C₉H₁₉, 6a–8a, and n-C₁₁H₂₃, 6b–8b) were synthesized in a reaction of aliphatic aldehydes 1a,b with glycerol 2 followed by separation in high yields of individual geometric isomers of cis-and trans-2-n-alkyl-5-hydroxy-1,3-dioxanes, cis-3a,b and trans-3a,b, followed by sulfation with sulfur trioxide-pyridine complex, and finally neutralization with NaOH, KOH, and NH₄OH, respectively. Physical data of the compounds and some surface properties of 2-n-nonyl derivatives, such as critical micelle concentration (CMC), effectiveness of aqueous surface tension reduction (Π_CMC), surface excess concentration Γ_CMC, and the surface area demand per molecule (A_CMC), were determined. It was shown that the surface activity of these compounds is influenced both by their geometric structure and by the monovalent counter-ion.     

Preparation and properties of sulfonate salt-type cleavable surfactants with a 1,3-dioxane ring

A series of di-anionic cleavable surfactants were prepared by the condensation of aldehydes with 2,2-bis(hydroxymethyl)-1,3-propanediol, followed by reaction with 1,3-propanesultone in the presence of sodium hydride. Surfactant 5a had a different¹H nuclear magnetic resonance spectrum in D₂O than products 5b−d. This was rationalized by its different conformation, which originates from the self-coiling of its alkyl chain. The critical micelle concentrations, Krafft points and hydrolysis properties of these surfactants were determined.     

Very long chain PUFA in murine testicular triglycerides and cholesterol esters

Very long chain (VLC) PUFA of the n−6 and n−3 series are known to occur in mammalian testis. The aim of this work was to characterize further two testicular lipid classes with VLCPUFA, cholesterol esters (CE) and total triglycerides (TG) in rat and mouse testis. The VLCPUFA predominating in these lipids were a series of n−6 pentaenes and tetraenes with 24 to 32 carbons, including small amounts of odd-chain PUFA, 28∶5n−6 and 24∶5n−6 prevailing in CE and TG, respectively. Most of the VLCPUFA of TG were concentrated in a small fraction of TG, made up by 1-O-alkyl-2,3-DAG. This TG subclass was absent altogether from the TG of sexually immature testis. The TG and the CE with VLCPUFA only occurred in testis of adult fertile animals. The proportion of VLCPUFA in total TG and CE was higher in rodents than in other mammals. In the n−6 PUFA-rich adult mouse testis, the amounts of testicular triacylglycerols decreased significantly after consumption of fish oil for 2 wk. Whereas 18∶2n−6 was significantly reduced, the amounts of 22∶5n−6 and longer n−6 PUFA were less affected in all mamor testicular lipids including PC and PE, where they were unchanged. The 1-O-alkyl-2,3-DAG and their n−6 VLCPUFA were virtually unaffected by the diet. The VLCPUFA-containing molecular species of CE and TG may represent a form of storage of cholesterol and polyenoic FA required to sustain spermatogenesis. Via chain-shortening, VLCPUFA stored in the neutral lipids may serve as precursors of the major C₂₂ PUFA typical of cell membrane glycerophospholipids, protecting testicular cells against shifts in FA composition induced by dietary changes.     

Alkoxyalkyl-substituted glycerol acetals: New hydrophobic intermediates for surfactant synthesis

In acid-catalyzed, one-step reactions of monofunctional alcohol (I) and glycerol mixture with a simple α,β-unsaturated carbonyl compound (acrolein, crotonaldehyde or methylvinyl ketone), four component glycerol acetals [mixtures ofcis-+trans-2-(2-alkoxyalkyl)-substituted derivatives of 4-hydroxymethyl-1,3-dioxolanes and 5-hydroxy-1,3-dioxanes] or two component glycerol ketals [mixtures ofcis-+trans-2-(2-alkoxyethyl)-2-methyl-4-hydroxymethyl-1,3-dioxolanes] were obtained, respectively. These compounds may be used as a new group of hydrophobic intermediates for synthesis of chemodegradable surfactants, which rapidly hydrolyze to nonsurfactant compounds in acidic aqueous solutions. Methods of synthesis, yields, compositions and chemical structures of components of reaction products, and products of their chemical degradation have been discussed. Part XX in the series: Acetals and Ethers. Part XIX, A. Piasecki,Polish J. Chem. 62:579 (1988).     

Influence of Spacer Nature on the Aggregation Properties of Anionic Gemini Surfactants in Aqueous Solutions

A series of anionic gemini surfactants with the same structure except the spacer nature have been studied. Their solution properties were characterized by the equilibrium surface tension and intrinsic fluorescence quenching method. The critical micelle concentrations (CMC), surface tension at cmc, C₂₀, and the micelle aggregation number (N) were obtained. The surface tension measurements indicate that these gemini surfactants have much lower cmc values and great efficiency in lowering the surface tension of water compared with those of conventional monomeric surfactants. Furthermore, the standard free energy of micellization for anionic gemini surfactants was also determined. The results showed that the nature of the spacer has an important effect on the aggregation properties of gemini surfactants in aqueous solutions. The surfactant with a hydrophilic, flexible spacer was more readily able to form micelle compared with the surfactant with a hydrophobic, rigid spacer, which leads to a lower CMC value, larger N, more negative free energy of micellization, and a more closely packed micelle structure.     

Synthesis and Some Properties of Fluorinated Cationic Surfactants

Three fluorinated cationic surfactants were prepared by condensing N-methyl diethanol amine pentafluoro benzoate with stoichiometric amounts of octyl, dodecyl or hexadecyl bromide. The surface properties and parameters were investigated to find the relationship between the structures of the hydrophobic portion of such compounds. The properties studied include surface tension, critical micelle concentration (CMC), effectiveness (Π_cmc), maximum surface excess (Γ_max) and minimum surface area (A_min) were investigated with respect to different concentrations at 25 °C. Standard free energies of micellization and adsorption of the prepared surfactants in the aqueous solution were studied. The values of Γ_max, standard free energies of micellization \Updelta \textG_\textmic^\texto \Updelta {\text{G}}_{\text{mic}}^{\text{o}} and adsorption \Updelta \textG_\textads^\texto \Updelta {\text{G}}_{\text{ads}}^{\text{o}} were found to increase with the chain length, while the cmc and minimum surface area occupied by one molecule A_min were found to decrease. The biocidal activity was determined through the inhibition zone diameter of prepared compounds which were measured against five strains of a representative group of microorganisms.     

Properties of aqueous solutions of disodium di-3-sulfopropyl α,θ-alkane dicarboxylate

A series of disodium di-3-sulfopropyl α,θ-alkane dicarboxylates NaO₃S(CH₂)₃OOC(CH₂)_nCOO(CH₂)₃SO₃Na (n=10, 12, 14, and 16) were prepared by the reaction of propane sultone with decane, dodecane, tetradecane or hexadecane dicarboxylic acids, and were estimated as to Krafft point and critical micelle concentration (cmc). The Krafft points of these α,θ-type surfactants were determined from the temperature at which the abrupt changes in the conductivities of the aqueous solutions in the presence of the solid surfactant were below 0 C for n=10, 23.5 C for n=12, 31.0 C for n=14 and 38.5 C for n = 16. The α,θ-type surfactant solution showed two break points in each plot of electroconductivity as a function of surfactant concentration. These results were considered to be due to the existence of the second cmc characteristic of these surfactants. A plot of the values obtained from the 1st cmc and the 2nd cmc of the α,θ-type surfactants decreases logarithmically according to the increasing total number of methylene groups (N). Their relationship is given as follows: log cmc =−0.142N+3.77 (1st cmc); log cmc =−0.143N+4.20 (2nd cmc).     

Synthesis and properties of N-(α-carboxyalkyl)acrylamide telomer-type surfactants having multihydrocarbon chains

N-(α-Carboxyalkyl)acrylamide telomer-type surfactants (xC _n−1 AmAc where n is alkyl chain length=6, 8, 10, 12; and x is degree of polymerization=3.3–13.1) were synthesized by the telomerization of monomer (C _n−1 AmAc) in the presence of the corresponding alkanethiol as a chain transfer agent and then investigated for their surface-active properties. xC _n−1 AmAc telomers lowered the surface tension of aqueous solutions that were at pH 9–10. The critical micelle concentrations (CMC) of the telomers were lower than those of the monomers with the same alkyl chain length, and the CMC values shifted to lower concentrations with both increasing alkyl chain length and polymerization degree. xC₉AmAc with x=3.3–6.3 gave the highest efficiencies in lowering the surface tension. The cross-sectional molecular areas per molecule of xC _n−1 AmAc telomers were smaller than the values estimated on the assumption that they are assemblies of C _n−1 AmAc monomer units. The foaming abilities and the foam stabilities were both in the orders of xC₇AmAc>xC₉AmAc>xC₅AmAc>xC₁₁AmAc. Mixtures of aqueous solutions of xC _n−1 AmAc telomers and toluene formed oil-in-water emulsions. The emulsion-stabilizing abilities were in the orders of xC₇AmAc>xC₅AmAc>xC₉AmAc=xC₁₁AmAc. The addition of Ca²⁺ to the mixed solutions of telomers and toluene resulted in formation of water-in-oil type emulsions. Thus, the surface-active properties of the telomers were influenced significantly by the alkyl chain length and the polymerization degree of the telomers. In addition, these properties could be correlated with the hydrophilic-lipophilic balance (HLB); the highest surface activities were observed by using xC _n−1 AmAc with HLB of 14–18.     

Synthesis and surface properties of chemodegradable anionic surfactants: Sodium (2-n-alkyl-1,3-dioxan-5-yl)sulfates

In the reaction of cis- and trans-2-n-alky-5-hydroxyl-1,3-dioxane mixtures with SO₃ · pyridine complex, followed by neutralization with sodium hydroxide or sodium carbonate, a new group of anionic surfactants, i.e., sodium cis- and trans-(2-n-alkyl-1,3-dioxan-5-yl)sulfates were obtained. The hydrophobic intermediates used in the sulfation reaction were obtained in high yields from four-component glycerol acetals by the process of transacetalization and selective crystallization of 1,3-dioxane derivatives. The physical data of the new compounds and some of their surface properties, such as critical micelle concentration (CMC), effectiveness of water surface tension reduction π_CMC, standard free energies of adsorption and micellization, ΔG _ads ^o and ΔG _CMC ^o , surface excess concentration, Γ_CMC, and the surface area demand per molecule, A_CMC, were determined. It was shown that the surface activity of the standard anionic surfactant sodium dodecyl sulfate should be similar to the surface activity of sodium (2-n-decyl-1,3-dioxan-5-yl)sulfate. Part XXX in the series: Chemical Structure and Surface Activity. Part XXIX: Sokołowski, A., B. Burczyk, and H.-R. Holzbauer, Adsorption of n-butyloligooxypropylene-pentaoxyethylene block copolymers at the aqueous solution-air interface, Collid Surfaces, in press.     

Elongation of (n−9) and (n−7)cis-monounsaturated and saturated fatty acids in seeds ofsinapis alba

Lipids in developing seeds ofSinapis alba contain appreciable proportions of (n−7)octadecenoic (vaccenic) acid besides its (n−9) isomer (oleic acid), whereas the constituent very long chain (>C₁₈) monounsaturated fatty acids of these lipids are overwhelmingly composed of the (n−9) isomers. Cotyledons of developingSinapis alba seed use [1-¹⁴C]acetate, [1-¹⁴C]malonate or [1,3-¹⁴C]malonyl-CoA for de novo synthesis of palmitic, stearic and oleic acids and for elongation of preformed oleic, vaccenic and stearic acids to their higher (n−9), (n−7) and saturated homologs, respectively. Moreover, elongation of preformed (n−7)palmitoleic acid to vaccenic acid is observed. Stepwise C₂-additions to preformed oleoyl-CoA by acetyl-CoA or malonyl-CoA yielding (n−9)icosenoyl-CoA, (n−9)docosenoyl-CoA and (n−9)tetracosenoyl-CoA are by far the most predominant reactions catalyzed by the elongase system, which seems to have a preference for oleoyl-CoA over vaccenoyl-CoA as the primer. The pattern of¹⁴C-labeling of the very long chain fatty acids formed from either acetate or malonate shows a close analogy in the mode of elongation of monounsaturated and saturated fatty acids.     

Synthesis,Characterization, Surface,and Thermodynamic Studies of Alkyl Tetrachloroferrates: Performance Evaluation of Their Nanostructures as Biocides

Decyl and dodecylamino tetrachloroferrates were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), elemental analysis, X-ray diffraction (XRD), nuclear magnetic resonance (¹H-NMR), and atomic absorption spectroscopy (AAS). The surface properties of the cationic surfactants including critical micelle concentration, effectiveness, minimum surface area, and maximum surface excess were determined using surface tension measurements. The effectiveness of surface tension reduction (π_cmc) was found to increase as the hydrophobic chain length increases with values of 30 and 34 mN m⁻¹ for C₁₀ and C₁₂, respectively. Moreover, the effect of temperature on micellization was determined over the range of 35–55 °C. Thermodynamic parameters (ΔG°, ΔS°, and ΔH°) were calculated and the results indicate a spontaneous process for both micellization and adsorption. The nanoparticles (NC₁₀ and NC₁₂) of the prepared surfactants were obtained using the ball mill technique. The particle size and morphology of the nanoparticles were determined using transmission electron microscope measurements. The antibacterial study of the nanoparticle surfactants revealed their strong efficiency against fungi and different pathogenic bacteria compared with the original surfactants.     

Synthesis and surface-active properties of trimeric-type anionic surfactants derived from tris(2-aminoethyl)amine

Trimeric-type anionic surfactants (3C_ntaAm, where n is a hydrocarbon chain length of 8, 10, or 12) with three hydrocarbon chains and three carboxylate headgroups were synthesized from tris(2-aminoethyl)amine, and their properties were investigated by surface tension, electrical conductivity, dynamic and static light-scattering, fluorescence of pyrene, and emulsification power techniques. The critical micelle concentrations (CMC) of 3C_ntaAm were 0.00092–0.00834 mmol dm⁻³, and the surface tensions at the CMC were 33.3–39.9 mN m⁻¹. The areas per molecule occupied by 3C₁₀taAm and 3C₁₂taAm were extremely small, showing they were highly compact at the air/water interface. In addition, adsorption or micellization behavior of 3C_ntaAm was estimated by parameters such as pC ₂₀ (the efficiency of surface adsorption), CMC/C ₂₀ (the ease of adsorption relative to the ease of micellization), and ΔG _M ^o (Gibbs energy of micellization). Dynamic and static light-scattering mesurements of 3C_ntaAm showed a hydrodynamic radius of 45–61 nm above the CMC and aggregation numbers of 10–82 at the CMC, respectively. The fluorescence intensity ratio of the first to the third band in the emission spectra of pyrene started to lower from far above the CMC for 3C₈taAm and 3C₁₀taAm, and below the CMC for 3C₁₂taAm. This suggests that loose micelles or premicellar aggregates are formed in solutions. Mixtures of aqueous solutions of 3C_ntaAm and toluene formed oil-in-water-type emulsions, and the stabilizing abilities were in the order of 3C₈taAm>3C₁₀taAm>3C₁₂taAm. The degree of emulsification of 3C₈taAm remained at 69% after 24 h of standing. Thus, 3C_ntaAm exhibited unique properties superior to monomeric or dimeric surfactants that were significantly influenced by their hydrocarbon chain lengths.     

Micellization Behavior of Cationic Gemini Surfactants in Aqueous-Ethylene Glycol Solution

The micellization behavior of gemini surfactants i.e. alkanediyl-α,ω-bis(cetyldimethylammonium bromide) (C₁₆-s-C₁₆,2Br⁻ where s = 3, 4, 10) in 10% (v/v) ethylene glycol solution was investigated by surface tension and conductometric measurements at 300 K. The critical micelle concentration, degree of micellar ionization, surface excess concentration, minimum surface area per molecule of surfactant, surface pressure at the CMC and Gibbs energy of adsorption of the dimeric surfactants have also been determined in the presence of different salts (NaCl, NaBr and NaI). The critical micelle concentration and degree of micellar ionization values decrease significantly in the presence of sodium halides and follows the sequence NaCl < NaBr < NaI. The free energy, enthalpy and entropy of micellization of dimeric surfactants in 10% (v/v) ethylene glycol solution were determined using the temperature dependence of the critical micelle concentration. The standard free energy of micellization was found to be negative in all the cases.     

Study on the Synthesis and Surface Active Properties of a Novel Surfactant with Triple Quaternary Ammonium Groups and Triple Dodecyl Chains Derived from Glycerin

The new triple chain surfactant was firstly prepared by ring-opening and a quaternization reaction with 2-(chloromethyl)-oxirane, tertiary amine and propane-1,2,3-triol as starting materials. The surfactant was characterized by MS and elementary analysis. Air–Liquid surface tension was measured by using a tensiometer at temperatures from 298 to 318 K respectively and in various salt solutions (NaX). The results show that with the increase of temperature, the values of critical micelle concentration (cmc) can achieve a minimum at 308 K. The maximum surface adsorption capacity Γ decreases, while the minimum molecule A _min area increases. With the increase in temperature and the decrease in counterionic diameter, the values of cmc decrease from 8.09 × 10⁻⁵ to 5.52 × 10⁻⁵ mol/L, and the adsorption capacity Γ increase from 1.80 × 10⁻¹⁰ to 2.74 × 10⁻¹⁰ mol/m², while there are almost no influences to surface tension (γ_cmc). The free energy of micelle formation is negative (−85.2 to −92.0 kJ/mol).