Sodium 10-undecenoate Research Articles

Equation-Oriented Mixed Micellization Modeling of a Subregular Ternary Surfactant System with Potential Medical Applications

The aqueous tricomponent surfactant mixture dodecyltrimethylammonium bromide (DTAB), sodium 10-undecenoate (SUD), and sodium dodecanoate (SDD) has been studied over the complete triangular diagram. This system is highly nonideal and has a coacervate domain. The mixtures do not precipitate in any proportion. There is a wide region of the phase diagram with positive deviations of the critical micelle concentration (CMC). The thermodynamic analysis has been done with the recently developed equation-oriented mixed micellization model (EOMMM) since the widely employed multicomponent regular solution theory (MRST) failed to represent this subregular ternary surfactant system. The advantages of the EOMMM over the MRST are discussed. The biocide properties of DTAB and SUD against microorganisms, the high CMCs that ensure high concentrations of biologically active monomers, and the possibility of having a system that remains liquid in any proportion make the present system attractive for the design of bactericide and antifungal preparations for the medicine, food, and cosmetic industries.

Effect of Double Bonds in the Formation of Sodium Dodecanoate and Sodium 10-Undecenoate Mixed Micelles in Water

The micellization of an aqueous mixture of sodium dodecanoate (SDD) and sodium 10-undecenoate (SUD) was studied with the theory of mixed micellization. A strong nonideality was found, with a preferential composition of mixed micelles. This phenomenon was interpreted on the basis of the interaction between the vinyl group and water by hydrogen bonding. The importance of the aliphatic pi electrons and water was stated.

Computational Study of the Structure and Behavior of Aqueous Mixed System Sodium Unsaturated Carboxylate-dodecyltrimethylammonium Bromide

The mixed surfactant system sodium 10-undecenoate (SUD)-dodecyltrimethylammonium bromide (DTAB) was studied by computational simulation to determine the composition and structure of the mixed microstructures. Results were contrasted with experimental data obtained from literature and our own laboratory. The modelization predicts spherical or cylindrical micelles with a preferential composition of SUD-DTAB of about 1:2, while the system predicts a lamellar structure with a proportion of 1:1 when SUD is replaced by the saturated soap sodium undecanoate. The model also predicts the deep inclusion of bromide ions in the micelle Stern layer. All predictions were in agreement with previous experimental results.

The nature of the coacervate formed in the aqueous dodecyltrimethylammonium bromide–sodium 10-undecenoate mixtures

The formation of a coacervate in mixtures of dodecyltrimethylammonium bromide (DTAB)–sodium 10-undecenoate (SUD) aqueous mixtures was studied by light scattering, ζ potential measurements, and electronic microscopy. The coacervate appears when the ζ potential goes to zero, and the energy barrier against agglomeration disappears, promoting the agglomeration of micelles. Rod-like micelles agglomerate in bundles in the DTAB-rich side of the phase diagram, while spherical or globular micelles agglomerate in clusters in the SUD-rich side. This difference explains the differences in the transition micelles–coacervate in the opposite sides of the two-phase region.

Unusual volumetric and hydration behavior of the catanionic system sodium undecenoate: sodecyltrimethylammonium bromide

Following the studies on the effect of double bonds in the surfactant hydrophobic tail on the formation of mixed surfactant aggregates, we studied the viscosity and density of the system Sodium 10-undecenoate (SUD)–decyltrimethylammonium bromide (DTAB)–water. We found that the partial molar volume (pmv) and intrinsic viscosity of both, micellised and unmicellised mixtures, are non-ideal, dependent on the mixture composition and related to structural changes in micelles. These phenomena are caused by the presence of the double bond at the distal extreme of the SUD molecule, which has some affinity with water by formation of hydrogen bonds. In particular, as far as we know, this is the first report on non-ideal behavior of the pmv in mixed micelles.

The aqueous cationic system sodium undecenoate-dodecyltrimethylammonium bromide at low concentration

The aqueous sodium undecenoate (SUD) –dodecyltrimethylammonium bromide (DTAB) catanionic system was studied at low concentration. The system did not precipitate, even at a 1:1 SUD:DTAB proportion, but showed the formation of a coacervate in a range of surfactant mixture compositions. Micelles have a preferential composition of 0.37 mole fraction of SUD. This behavior is attributed to the presence of the double bond at the distal extreme of the SUD molecule, which can form hydrogen bonds with water. Consequently, the –CH=CH2 group is situated at the interface between the hydrocarbon micelle core and water, reducing the interfacial free energy. Structural computations demonstrate that the mentioned SUD proportion produces complete coverage of the micelle surface by the double bonds.

The polymerisation of aqueous sodium undecenoate mesophases

Sodium 10-undecenoate is a polymerisable surfactant having a double bond in the ω position of its chain. This surfactant has been polymerised by McGrath, both in lamellar and hexagonal mesophases by thermal and photochemical initiation, and she obtained relatively low conversions. She could not obtain the polymerisation kinetics. We have polymerised both liquid crystals by irradiation by γ-rays, and we obtained higher conversions: 91.6±0.7% in 50 wt% of surfactant in water (hexagonal mesophase), while McGrath obtained 56% by thermal and 20.6% by photochemical polymerisation; and a maximum of 59.5% in 75 wt% of surfactant in water (lamellar liquid crystal). McGrath obtained conversion values of 24% (thermal initiation) and 19.2% (photochemical initiation) for this mesophase. We could not obtain the polymerisation kinetics of the 50 wt% sample. Even at the lowest irradiation dose the conversion rendered the maximum value. The 75% sample showed a measurable polymerisation increase with γ-radiation dose until 60 kGy, but a large decomposition was observed at 80 kGy. This decomposition, caused by an excess of radiation, is not exceptional. The Fourier transform IR study of the different kinds of water in the system (bulklike water, water related to surfaces and water molecules trapped in the interstices of the microstructures) indicates that there was no significant transformation of the structure during the irradiation; the values of the nonirradiated liquid crystal remained almost unchanged.

Low-concentration aqueous solutions of undecenoic acid and sodium undecenoate

The behaviors of low-concentration aqueous solutions of 10-undecenoic acid and its sodium salt were studied by several techniques. The acid does not have a critical micelle concentration, but gives an emulsion of very small droplets at (0.8–1) × 10−4 mol dm−3. The emulsion was clearly visible by eye at 0.002 mol dm−3. The sodium salt has a stepwise aggregation process, giving premicellar aggregates at 0.023 ± 0.008 mol dm−3, which grow to form micelles at 0.117 ± 0.007 mol dm−3. The compositions of the solution and the micelles were also studied.

Mechanism of the immobilization of surfactants on polymeric surfaces by means of an argon plasma treatment: Influence of UV radiation

The mechanism of the immobilization of the surfactant sodium 10-undecenoate (C11(:)) on poly(ethylene) (PE) by means of an argon plasma treatment has been investigated. In particular, the influence of the vacuum ultraviolet (UV) radiation emitted by the argon plasma on the immobilization was studied. For this purpose, PE samples were coated with C11(:) (PE/C11(:) samples) and treated with an argon plasma under different conditions. PE/C11(:) samples were placed inside (glow) and outside (afterglow) the visible region of the plasma. Additionally, polymer samples that were placed in the glow of the plasma were covered with lithium fluoride or quartz crystals. These materials are transparent for electromagnetic radiation with a wavelength longer than 104 and 150 nm, respectively. Derivatization X-ray Photoelectron Spectroscopy was applied to characterize the modified polymer surfaces. It was demonstrated that vacuum UV radiation with a wavelength shorter than 150 nm made a predominant contribution to the process of immobilization. Under certain conditions it was possible to retain about 30% of the functional groups of the initially coated surfactant layer on PE. Furthermore, the UV radiation accounted for etching of PE and PE/C11(:) surfaces and initiated oxidation of the polymer surfaces.

Coating of Anionic Surfactants onto Poly(ethylene) Surfaces Studied with X-ray Photoelectron Spectroscopy

Poly(ethylene) (PE) samples were immersed in aqueous solutions of different anionic surfactants, viz. sodium dodecane sulfate (SDS), sodium 10-undecene sulfate (S11(:)), and sodium 10-undecenoate (C11(:)). When the PE samples were removed from the solutions, dried, and analyzed with X-ray photoelectron spectroscopy (XPS), surfactant was detected at the surface only if the PE samples were wetted by the surfactant solution. Wetting was accomplished by pretreating the polymer with an argon plasma for 5 s. In this way, a relatively hydrophilic surface was obtained with advancing and receding water contact angles of 89° and 31°, respectively. In a second approach, 1 vol % of hexanol was added to the surfactant solutions, thereby decreasing the surface tension of the solutions to a value below 31 mN/m, allowing direct coating of PE with the surfactants. XPS was performed to estimate the orientation of the molecules in the surfactant layer at the surface. Surfactant molecules were randomly oriented in a homogeneous layer. The thickness of this layer varied from 10 to 60 A and increased with increasing surfactant concentration of the immersion solution.

Preparation of heparin-like surfaces by introducing sulfate and carboxylate groups on poly(ethylene) using an argon plasma treatment

Carboxylate and sulfate groups were introduced at the surface of poly(ethylene) (PE) samples.This was accomplished by coating and immobilizing sodium 10-undecenoate (C11(:)) and 10-undecenesulfate (S11(:)) on the polymer by means of an argon plasma treatment. The composition of the coatedsurfactant layer was proportional to the composition of the coating solution. The thickness of the surfactantlayer on the surface of PE samples, which were precoated from an aqueous solution with a total surfactantconcentration of 0.30 M, was about 55 A°. The presence of carboxylate and sulfate groups after plasmatreatment of the precoated surfaces was confirmed by X-ray photoelectron spectroscopy (XPS). About20% of the initial amount of functional groups of the coated surfactants was retained at the PE surface.The ratio of carboxylate/ sulfate groups at the plasma treated surfaces was dependent on the compositionof the precoated surfaces. The minimum surface density of these groups on the resulting samples wasabout one group per 40 A°2.

Introduction of Carboxylate Groups at Poly(ethylene) Surfaces by Argon Plasma Immobilization of Sodium Salts of Fatty Acids

Carboxylate groups were introduced at poly(ethylene) (PE) surfaces by immobilization of sodium 10-undecenoate (C11(:)) or sodium dodecanoate (C12) using an argon plasma treatment. The presence of carboxylate groups at the surface was confirmed by ATR-FTIR spectroscopy, contact-angle determinations, and derivatization XPS. The presence of an unsaturated bond in the alkyl chain of the surfactant enhanced the immobilization process. About 28% of the initial amount of carboxylate groups in the precoated C11(:) layer was retained at the PE surface after plasma treatment, as compared to only 6% for the C12 layer. No changes in the wettability of the modified PE surfaces were observed when they were stored at room temperature for at least 12 weeks. The use of the carboxylate groups that were introduced at polymeric surfaces with this method for further covalent coupling of other molecules is discussed.

Formation of CdS nanoparticles in mixed cationic-anionic surfactant vesicle system

CdS nanoparticles were prepared in a mixed vesicle dispersions of the simple cationic and anionic surfactants, i.e. decyltrimethylammonium bromide and sodium 10-undecenoate, from Cd 2+ or CdEDTA 2− and H 2S. UV-visible spectra were used to characterize the CdS particles formed. The particle size (in diameter) varied from 2.7 to > 5.0 nm, depending on the preparation conditions. When the pH is between 9.4 and 10.0, at which the vesicles have the maximum entrapping efficiency, the smallest particles with good stability and relative narrow dispersion are obtained. The inner and outer surfaces are all available for the formation of ultrafine CdS particles. The CdS nanoparticles generated from Cd 2+ are obviously smaller and much more stable than those generated from CdEDTA 2−.

Interactions of Polymerized Surfactants and a Polymer

The interactions of polymerized surfactants and hydrophobically modified ethyl hydroxyethyl cellulose (HMEHEC) have been investigated in terms of their viscosities. Three polymerizable surfactants used were sodium 10-undecenoate (SUD), sodium 11-(N-ethylacrylamido)undecanoate (SEAAU), and zwitterionic (((acryloyloxy)undecyl)dimethylammonio)acetate (AUMAA). These polysoaps exerted varying degrees of hydrophobic interactions with HMEHEC via the formation of mixed micelles as clusters of physical crosslinks. Polymerized SEAAU showed a 27-fold increase in the viscosity of the mixed system, but the effect was much inferior for the other two systems. The copolymers of the surfactants and styrene also interacted rather strongly with HMEHEC. The dominating effect of electrostatic charges on the viscosity is demonstrated by the marked difference between the system with negatively charged poly(SEAAU) and that with the charge-neutral poly(AUMAA).

Vesicles from Mixed Sodium 10-Undecenoate-Decyltrimethylammonium Bromide Solutions

Unilamellar vesicles were prepared from aqueous mixtures of sodium 10-undecenoate and C 10NMe 3Br with molar ratios from 9:1 to 1:9. The existence of vesicles was demonstrated by negative-staining TEM, freeze-fracture TEM, bromphenol blue entrapment, and quasi-elastic light-scattering experiments. In general, the diameters of the vesicles ranged from 200 to 1000 Å. The vesicles formed from the nearly equimolar ratio solutions have a larger mean size. The bilayer structure of a vesicle was observed by negative-staining TEM. The vesicles showed two phase transition temperatures, which varied with the sodium 10-undecenoate: C 10NMe 3Br molar ratio. The highest temperatures corresponded to the samples with 1:1 ratios. The vesicles remained stable for at least 70 days at room temperature and in at least 25% ( v/ v) ethanol solution. It is suggested that the strong interaction between the cationic and anionic ions is a prerequisite for the formation of the vesicles. The composition of vesicles varied with the sodium 10-undecenoate:C 10NMe 3Br ratio in solutions, and micelles and vesicles existed simultaneously.

Immobilization of alkoxylated phosphine ligands and their Rh complexes to a silica surface coated with an organic mono- or multilayer

A new methodology for the immobilization of homogeneous catalysts on a modified silica surface is suggested. Phosphine ligands with polar substituted groups as well as their rhodium carbonyl complexes are attached to modified silica substrates. The modified silica substrates were prepared by either depositing a crosslinked poly(hydroxyethyl methacrylate) network on the surface of porous silica, or by transforming the surface-pendant hydroxyl groups of silica into [3-(siloxysilyl)propyl]-ethylenediamine groups. They are denoted as P(HEMA-MBAM) /SiO 2 and SSPEDA/SiO 2, respectively. The following phosphine ligands were attached to the modified silica: (1) α,ω-bis(diphenylphosphino)-poly(ethylene glycol) (DPP-PEG); (2) 2-methoxy-methylenephenyl-diphenylphosphine (MPDPP); and (3) 1,2-bis{[(2-methoxyacetylphenyl)-phenyl-(diphenyl)]phosphino}ethane (MAPDPPE). The FT-IR investigations of these immobilized catalysts revealed hydrogen bonding between the surface-pendant hydroxyl or amino groups and the oxygen atoms of the phosphine ligands. The SEM and EDS surface analyses showed that the phosphine rhodium carbonyl complexes were uniformly distributed over the polymer coated silica. Hydroformylation reactions of several olefins were employed for the assessment of the efficiency of immobilization, and both hydrophobic (cyclohexane) and hydrophilic (water) reaction media have been employed. The time dependence of the hydroformylation of 2-(±)-ethylhexyl acrylate (EHA) in a hydrophobic medium indicated that the modified silica surfaces are more compatible with the hydrophobic reactant molecules than the pure silica surface, and that SSPEDA/SiO 2 is more effective than P(HEMA-MBAM)/SiO 2. The much higher hydroformylation rate for sodium 10-undecenoate (UDNa) than for 1-vinylimidazole when water was used as reaction medium is due to the higher ability of the former surface active molecules to be adsorbed on the catalyst surface. Successive reuses of the immobilized catalysts in the hydroformylation of ethyl 10-undecenoate in cyclohexane have demonstrated that MAPDPPE provides stronger immobilization than MPDPP.

Copolymerization of Sodium 10-Undecenoate with Sodium 3-Allyloxypropionate

The copolymerization of sodium 10-undecenoate (UANa) with sodium 3-alloyoxypropionate (APNa) was examined under irradiation with UV light. The copolymerization rate was lower than homopolymerization rates of UANa and APNa. Each copolymer showed only one peak in the gel permeation chromatogram, which suggests that copolymerization really occurs, although the number-average degree of polymerization (DPn) of the copolymers differed depending on composition of monomer feed in the copolymerization system. DPn of the copolymer increased from 12 to 30 with APNa in the monomer feed. Reactivity ratios of the monomers were rUANa=0.65±0.22 and rAPNa=0.63±0.27. Critical micelle concentration (CMC) and pre-CMC of the copolymer, estimated from the UV absorption spectrum of Methylene Blue added to the aqueous solution of the copolymer, increased with APNa unit in the copolymer. The maximum amount of solubilized benzene into the aqueous solution of the copolymer increased with concentration of the copolymer higher than its pre-CMC, and decreased with increasing APNa unit in the copolymer.

Aggregation states and polymerizabilities of amphiphilic monomer molecules in aqueous systems with different water contents

Molecular aggregation states of sodium and zinc 10-undecenoates in aqueous systems with different water contents were investigated in relation to their polymerizabilities. The aggregation states were examined by thermal analysis, and γ-ray-initiated post-polymerization in various states was monitored by IR spectral changes. In the case of sodium 10-undecenoate, coagel and gel states with lamellar structures and a liquid crystal state consisting of a regular hexagonal array of cylindrical aggregates of the molecules can appear, depending on the temperature in the range of water contents of 30–60%. However, zinc 10-undecenoate exhibits coagel, gel-I, gel-II and lamellar liquid crystal states in a wide range of water contents. The polymerizability of the sodium salt increased in the order coagel, gel and liquid crystal with a hexagonal structure, whereas the zinc salt polymerized most effectively in the gel-I phase with a regular lamellar structure. It is concluded that the regular arrangement of the monomer molecules together with conformational freedom is an important factor for the polymerization.

Catalytic Activity of Poly(α-sulfoundecenoic acid)

Poly(α-sulfoundecenoic acid), poly(SUA-H), was prepared from poly(undecenoic acid), poly(UA-H). The critical micelle concentration, CMC, and pre-CMC of poly(SUA-H), estimated with measurement of electric conductivity of the aqueous solution, were slightly higher than those of poly(sodium undecenoate), poly(UA-Na), and benzene was solubilized into aqueous solution of poly(SUA-H) at the concentrations above the pre-CMC. Catalytic activity of poly(SUA-H) on the acid hydrolyses of sucrose and p-nitrophenyl acetate, PNPA, was examined. For the hydrolysis of sucrose in water, the catalytic activity of poly(SUA-H) was slightly lower than that of hydrochloric acid and the catalysis followed an ordinary second-order kinetics. For the hydrolysis of PNPA in ethanol-water mixture (1:1 in vol.), the catalytic activity was slightly higher than that of hydrochloric acid, although the catalysis seemed to follow an ordinary second-order kinetics. For the hydrolysis of PNPA in water, however, catalytic activity was found to be considerably higher than those of hydrochloric acid and low molecular weight analog of poly(SUA-H). The reaction rate showed a saturation phenomenon with increasing concentration of poly(SUA-H), although it increased proportionally with increasing concentration of PNPA in the examined range. Lineweaver-Burk plots of the kinetic data showed good straight lines, which indicated that the catalysis followed a Michaelis-Menten type kinetics. These results can be explained by hydrophobic interactions of the catalyst with the substrate.

Liquid crystals formed in sodium alkyl sulfates-water systems studied by positron annihilation techniques

Lyotrophic phase transitions were investigated in liquid crystalline systems of sodium alkyl sulfate-water. The positron annihilation parameters indicated the presence of a nematic phase in sodium dodecyl sulfate water-system in absence of additives. The effect of the hydrocarbon chain-length and unsaturation of the surfactant on the nematic phase formation were also studied. Liquid crystals of sodium 10-undecenoate were polymerized by ultraviolet irradiation. Polymerization is seen to cause a gradual change from the hexagonal to the lamellae phase.