Polymerized Surfactant Vesicles

Irradiation of surfactant vesicles prepared from (C₁₈H₃₇)₂ N⁺(CH₃)C₆H₄-CHCH₂p,CT⁻, 1, [C₁₅H₃₁CO₂(CH₂)₂]₂N⁺(CH₃)CH₂C₆H₄CHCH₂,CL⁻ 2, and (C₁₈-H₃₇)₂N⁺(CH₃)CH₂CH₂OCOC₆H₄CHCH₂p,Br⁻, 3, by ultraviolet light or by bursts of 266 nm laser pulses have resulted in the loss of styrene absorbances. This process has been accounted for in terms of a model which considers intravesicular surface reactions to give polymers with average chainlength of 22. Degreees of photopolymerization have been determined in vesicles prepared from 3 subsequent to separating the polystryrene, formed in the photolysis, from the surfactants. Vesicle surface photopolymerizations result in aqueous cleft formation and in enhanced stabilities. Polymerized vesicles provide media for in situ generation of colloidal catalysts and semiconductors.     

A thermosensitive chitosan/poly(vinyl alcohol) hydrogel containing nanoparticles for drug delivery

The synthesis and characterization of a thermosensitive chitosan (CS)/poly(vinyl alcohol) (PVA) hydrogel containing nanoparticles with different charges for drug delivery were reported. Through the electrostatic effect of –N⁺(CH₃)₃ and –COO⁻, the nanoparticles of N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride(HTCC)–carboxymethyl chitosan (CM) were prepared. The nanoparticles with different charges were obtained by the different ratio of –N⁺(CH₃)₃ and –COO⁻, which were suitable for drug delivery with opposite charges, such as propranolol and diclofenac sodium, respectively. The release of the positive drug was the slowest with the hydrogels containing negative nanoparticles. Similarly, the release of the negative drug was the slowest with the hydrogels containing positive nanoparticles. However, the releases of the two drugs were both the fastest with the pure hydrogels. It indicated the addition of nanoparticles was helpful to slow the suitable drug release. Though the nanoparticles did not reinforce the gel strength, the electrostatic effect between nanoparticles and drugs reduced the burst release. Therefore, the composite gels are attractive for applications as carriers for drug delivery.     

Single‐Pot Ethane Carboxylation Catalyzed by New Oxorhenium(V) Complexes with N,O Ligands

The oxorhenium(V) chelates [ReOCl(N,O‐L)(PPh₃)] [N,O‐L=(OCH₂CH₂)N(CH₂CH₂OH)(CH₂COO) ( 2 ), (OCH₂CH₂)N(CH₂COO)(CH₂COOCH₃) ( 3 )] and [ReOCl₂(N,O‐L)(PPh₃)] [N,O‐L=C₅H₄N(COO‐2) ( 4 ) C₅H₃N(COOCH₃‐2)(COO‐6) ( 5 )] have been prepared by reaction of [ReOCl₃(PPh₃)₂] ( 1 ), in refluxing methanol, with N,N‐bis(2‐hydroxyethyl)glycine [bicine; N(CH₂CH₂OH)₂(CH₂COOH)], N‐(2‐hydroxyethyl)iminodiacetic acid [N(CH₂CH₂OH)(CH₂COOH)₂], picolinic acid [NC₅H₄(COOH‐2)] or 2,6‐pyridinedicarboxylic acid [NC₅H₃(COOH‐2,6)₂], respectively, with ligand esterification in the cases of 3 and 5 . All these complexes have been characterized by IR and multinuclear NMR spectroscopy, FAB⁺‐MS, elemental and X‐ray diffraction structural analyses. They act as catalysts, in a single‐pot process, for the carboxylation of ethane by CO, in the presence of potassium peroxodisulfate K₂S₂O₈, in trifluoroacetic acid (TFA), to give propionic and acetic acids, in a remarkable yield (up to ca. 30%) and under relatively mild conditions, with some advantages over the industrial processes. The picolinate complex 4 provides the most active catalyst and the carboxylation also occurs, although much less efficiently, by the TFA solvent in the absence of CO. The selectivity can be controlled by the ethane and CO pressures, propionic acid being the dominant product for pressures about ca. 7 and 4 atm, respectively (catalyst 4 ), whereas lower pressures lead mainly to acetic acid in lower yields. These reactions constitute an unprecedented use of Re complexes as catalysts in alkane functionalization.     

Synthesis of highly ordered supermicroporous silica using short-chain cationic trimeric surfactant as structure-directing agent

Highly ordered supermicroporous silica was synthesized by short chains cationic trimeric surfactant [C₁₀H₂₁N⁺(CH₃)₂(CH₂)₂N⁺(CH₃)(C₁₀H₂₁) (CH₂)₂N⁺(CH₃)₂C₁₀H₂₁] · 3Br⁻ (denoted C_10-2-10-2-10) with a short spacer group (s = 2) as the structure-directing agent and tetraethyl orthosilicate as the precursor. The obtained samples were characterized by small-angle X-ray diffraction, high resolution transmission electron microscopy, and N₂ adsorption–desorption. The results showed that the pore structure of the resulting samples belonged to the two-dimensional hexagonal structure (space group 2D-p6mm) with a pore size from 1.92 to 2.16 nm, which was within the supermicroporous range. The high-quality supermicroporous silica was formed at a low molar ratio of C_10-2-10-2-10 to tetraethyl orthosilicate (0.08:1), which indicated that the self-assembly ability of C_10-2-10-2-10 was stronger than that of corresponding monovalent surfactants. We strictly compared the methods of calculating surface area and pore size of supermicroporous materials, and the surface area was found to be in the range of 910–1,135 m² g⁻¹ by the α_s plot method. With the increase of hydrothermal temperature, the ordering of the supermicroporous structure increased first then decreased, at the same time the pore size was enlarged.     

Soluble polymers of monosubstituted acetylenes with quaternary ammonium pendant groups: structure and morphology

Soluble conjugated polymers were obtained in the presence of Pd(II), Pt(II) and Rh(I) complexes from monosubstituted acetylene 3‐dimethylamino‐1‐propyne (H? C≡CCH₂N(CH₃)₂, 1 ) and the corresponding hydrochloride (H? C≡CCH₂N(CH₃)₂·HCl, 2 ) and hydrobromide (H? C≡CCH₂N(CH₃)₂·HBr, 3 ) derivatives. A series of reactions were performed to achieve the optimization of the polymerization conditions. The highest yields were found for polymers synthesized using Pd(II) bisacetylides specially prepared, i.e. trans‐[Pd(PPh₃)₂(C≡CCH₂N(CH₃)₂)₂], trans‐[Pd(PPh₃)₂(C≡CCH₂N(CH₃)₂)₂HCl] and trans‐[Pd(PPh₃)₂(C≡CCH₂N(CH₃)₂)₂HBr], respectively. The dimension and size distribution of the polymers were investigated using dynamic light scattering. Polymers containing quaternary ammonium groups showed evidence of a hydrodynamic radius of about 300 nm if prepared with the Rh(I) catalyst and of 160 nm if prepared with the Pd(II) catalysts. Polymers obtained from 1 showed smaller hydrodynamic radius compared to polymers obtained from 2 and 3 , regardless the polymerization catalyst. The ionic polymeric materials were soluble in organic solvents and, more interestingly, in water. The formation of nanoparticles with pearl‐like morphology was achieved using a recently developed osmosis‐based method, with dimensions varying from 60 nm up to micrometres. Copyright © 2011 Society of Chemical Industry     

Influence of Substructures on the Spreading Ability and Hydrolysis Resistance of Double-Tail Trisiloxane Surfactants

Four types of novel double-tail trisiloxane surfactants of the general formula Me₃SiOSiMeR¹OSiMe₃ (R ¹ = –(CH₂)₃NR²CH₂CH(OH)CH₂(OCH₂CH₂)_xOCH₃; R ² = –CH₂CH(OH)CH₂OCH₂(CH₂)_yCH₃, –CH₂(CH₂)₃CH₃, –CH₂CH₂CH(CH₃)₂; x = 8.4, 12.9, 17.5, 22; y = 2, 6), have been synthesized. Their structures were characterized by proton and carbon nuclear magnetic resonance. Most of them are able to reduce the surface tension of water to less than 24 mN/m at concentration levels of 10⁻⁵ mol/L and 10⁻⁴ mol/L. The emphasis was on the influence of substructures on their spreading ability and hydrolysis resistance. The results showed that a weaker hydrophilicity of a surfactant molecule, a larger molar ratio of methyl to methylene in the whole hydrophobic groups, more flexible hydrophobic groups and introduction of a methyl group in the spacer can all improve the spreading ability of the double-tail trisiloxane surfactant solutions on low-energy solid surfaces. The double-tail trisiloxane surfactants 1F and 2F are stable for more than 270 days in a neutral environment (pH 7.0). The hydrolysis resistance of the double-tail trisiloxane surfactants can be improved by a weaker hydrophilicity of the surfactant molecule, and a larger volume of the hydrophobic groups.     

Synthesis and Properties of Novel Double-Tail Trisiloxane Surfactants

To improve the hydrolysis resistant ability of trisiloxane surfactants, ethoxylated single-tail and double-tail trisiloxane surfactants of the general formulas Me₃SiOSiMeR¹OSiMe₃ (R ¹ = (CH₂)₃NHCH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; x = 8.4, 12.9, 17.5, 22) and Me₃SiOSiMeR²OSiMe₃ (R ² = (CH₂)₃NR³CH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; R ³ = CH₂(CH₂) _y CH₃; x = 8.4, 12.9, 17.5, 22; y = 2, 6) were synthesized. Their structures were characterized by ¹H NMR and ¹³C NMR. The surface activity and hydrolysis resistant properties of the trisiloxane surfactants prepared were also studied. The values of the critical micelle concentration of all trisiloxane surfactants prepared were at levels of 10⁻⁵ and 10⁻⁴ mol/L. They can reduce the surface tension of water to less than 24 mN/m. The hydrolysis resistant properties of double-tail trisiloxane surfactants are superior to those of single-tail trisiloxane surfactants. The double-tail trisiloxane surfactants 1B (x = 8.4; y = 2) and 2C (x = 12.9; y = 6) can be stable for 8 days in an acidic solution (pH 4.0) and 11 days in an alkaline environment (pH 10.0).     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Synthesis and Characterization of a Quaternized Glucosamide-Based Trisiloxane Surfactant

The synthesis of quaternized glucosamide‐based trisiloxane surfactant (QGS) of the general formula Me₃SiOSiMeR¹OSiMe₃ (R¹ = (CH₂)₃N⁺(CH₃)₂(CH₂)₂R², R² = glucosamide group) was described, and the surface activity properties of the surfactant were studied. The N‐[2‐(dimethylamino)ethyl]‐d ‐gluconamide was synthesized by amidation of the ethylenediamine with d ‐gluconolactone. The 3‐(3‐chloropropyl)‐1,1,1,3,5,5,5‐heptamethyltrisiloxane was prepared by the acid‐catalyzed reaction of a silane monomer. The QGS was prepared by quaternization of the precursor halogenated hydrocarbon with a tertiary amine. They were structurally characterized by IR, ¹H NMR and MS. And it reduced the surface tension of water to approximately 21 mN m^?1 at concentration levels of 10^?3 mol L^?1.     

Ferrocene-Based Cationic Surfactants: Surface and Antimicrobial Properties

A novel series of ferrocenyl surfactants was synthesized by the reaction of ferrocene disulfonic acid with different primary and tertiary fatty amines to produce the corresponding ammonium salts Fc[SO₃ ^{− +}NH₃(CH₂) _n CH₃]₂, where n = 9, 11, or 15 and Fc[SO₃^{− +}NH(CH₃)₂(CH₂) _n CH₃]₂, where n = 7 or 11, respectively, and where Fc = ferrocene. Chemical structures were confirmed by microelemental analysis, FTIR, and ¹H NMR spectroscopy. The critical micelle concentration of each prepared surfactant was determined using equilibrium surface tension. Furthermore, air/water interface parameters including effectiveness (π _CMC), efficiency (Pc₂₀), maximum surface excess (Г_max), and minimum surface area (A _min) were determined at 30, 40, and 50 °C. Thermodynamic parameters (ΔG°, ΔS°, and ΔH°) for both micellization and adsorption processes were recorded. The new synthesized surfactants were screened as antimicrobial agents against different bacterial and fungal organisms.     

Characterization of octadecyltrichlorosilane self-assembled monolayers on silicon (100) surface

Both monolayers and multilayers were obtained from a dilute solution of n-octadecyltrichlorosilane [OTS, CH₃(CH₂)₁₇SiCl₃] on a SiO₂/Si surface after a low pressure O₂ plasma treatment. A close-packed monolayer of good quality was formed on the SiO₂/Si surface. The resulting self-assembled layers were characterized by goniometry, atomic force microscopy (AFM), ellipsometry and Fourier transformed infrared attenuated total reflection (FTIR-ATR) spectroscopy. An examination of the time-dependent water contact angle measurements as a function of the OTS concentration revealed rapid monolayer formation at the initial stage. The contact angle measurements showed that the surface structure of the OTS monolayer was quite resistant to environmental changes as a result of the polymerization of OTS molecules and the formation of covalent bonds between the monolayer and substrate surface. The surface was covered with islands (observed by AFM) that were in-filled to produce in a smooth surface. The FRIR-ATR spectra showed symmetric (νs(CH₂)) and asymmetric (νas(CH₂)) components perpendicular to the surface.     

Effect of Temperature on Structural and Optical Properties of Boehmite Nanostructure

The nanocrystalline boehmite, γ‐AlOOH, was synthesized by the hydrothermal method using AlCl₃·6H₂O and urea as precursors, and the effect of different annealing temperatures resulting in different phases of alumina (Al₂O₃) was obtained. The effects of different temperature on the phase and micrographs of the prepared γ‐AlOOH nanostructures were investigated. The obtained products were characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy techniques. The XRD results show that with the increasing temperature, the transformation of boehmite into well‐crystallized α‐Al₂O₃ and the morphology from nanoplatelets with spindle‐like edges to vermicular structure take place. The crystallite size and lattice parameters were calculated by Rietveld refinement. The convincing evidence for the crystal phase of the as‐prepared and annealed samples was provided by FTIR spectra. The Raman spectra unveil the change in vibrational modes of the phase transition alumina.     

Mechanical properties of sol–gel prepared nanocomposite coatings in the presence of titania and alumina-derived nanoparticles

Hybrid nanocomposite coatings were prepared by sol–gel method using silica, titania and alumina nanoparticles derived from their alkoxides precursors; in the presence of 3-glycidoxypropyl-trimethoxysilane (GPTMS) and bisphenol A (BPA) on 1050 aluminium alloy substrate. The effect of type and ratio of nanoparticles on mechanical behaviour of the coatings were investigated by dynamic mechanical thermal analysis (DMA) and nanoindentation experiments. DMA results demonstrated that the values of the glass transition temperature (T_g) and the temperature at maximum tan (δ), (T_t) as well as the storage modulus of the hybrid samples depend mainly on the silane content and titania to alumina molar ratio of nanoparticles in the coating composition. In addition, nanoindentaion experiments were performed to study the mechanical properties such as hardness, elastic modulus and E/H ratio for the nanocomposite hybrid coatings. Nanoindentation results indicate that the homogenous reinforced structure was formed in the surface of nanocomposite coating with incorporation of titania and alumina-derived nanoparticles. The incorporation of TiO₂ in comparison with AlOOH nanoparticles in the GPTMS-based coatings showed an improving effect on E/H ratio.     

Transformation of cubic AgBiS2 from nanoparticles to nanostructured flowers by a microwave-refluxing method

Cubic AgBiS₂ nanoparticles and flower-like clusters were successfully synthesized by microwave refluxing of CH₃COOAg, Bi(NO₃)₃·5H₂O and thiosemicarbazide (NH₂NHCSNH₂) in ethylene glycol. The phase was detected by X-ray diffraction (XRD) and selected area electron diffraction (SAED). The SAED pattern was also in accordance with that of the simulation. Scanning and transmission electron microscopy (SEM and TEM) revealed the gradual transformation of nanoparticles into flower-like clusters by increasing microwave power. Their UV–visible absorption and photoluminescence (PL) emission were detected by spectrometry. Possible formation mechanism of nanoparticles and nanostructured flowers was also proposed according to the experimental results.     

Surface activity and premicellar aggregation of some novel diquaternary gemini surfactants

A series of novel cationic gemini surfactants, C _n H _2n+1 N⁺(CH₃)₂CH₂CHOHCHOHCH₂N⁺(CH₃)₂C _n H _2n+1 ·2Br⁻, have been synthesized, and their surface properties were investigated in water, 0.1 N NaCl, and 0.1 N NaBr at 25°C. From surface tension-log molar concentration plots, the pC₂₀, critical micelle concentration (CMC), and γ_CMC values have been determined, and the area/molecule at the aqueous solution/air interface was calculated. When the number of carbon atoms in the alkyl (hydrophobic) chains is above a certain number, which depends upon the molecular environment, the surface activity of the compounds is less than expected. This appears to be due to formation of small, soluble aggregates below the CMC. Equilibrium constants calculated for this aggregation indicate that a series of oligomers are formed.     

Creation of a functional polysiloxane layer on the surface of magnetic nanoparticles using the sol-gel method

The developed methods using tetraethoxysilane and trifunctional silanes were applied to obtain Fe₃O₄ magnetic particles that contain amino groups with compositions of ≡Si(CH₂)₃NH₂, ≡Si(CH₂)₃NH(CH₂)₂NH₂, and [≡Si(CH₂)₃]₂NH. The XRD data show that the nuclei of nanoparticles in the obtained materials preserve the structure of the primary carrier, namely, that of Fe₃O₄ magnetite. The thermograms show a high thermal stability of the applied surface layers, i.e., their destruction was found to start at temperature above 250°C. The DRIFT spectra indicate the formation of the silica bond framework in the surface layers of nanoparticles and also the existence of hydrogen bonds between amino groups and silanol groups with the participation of water molecules aided. All of the obtained materials exhibit magnetic properties and offer promising application in medicine.     

Molecular adsorption of n-alkyl amines,carboxylic acids,and amides onto well-defined,polar organic surfaces

This paper details the formation of oriented monolayer films by the solution-phase adsorption of n-alkyl-chained adsorbates (CH₃(CH₂)_n-1Y) onto the polar surfaces of terminally-substituted self-assembled monolayers (SAMs; Au/S(CH₂)_mX). The polar tail groups (X and Y) of the adsorbate and SAM included amine, carboxylic acid, and amide groups, and the formation of the adsorbed monomolecular films on the SAMs relied on non-covalent interactions between X and Y. Highly organized monomolecular adlayers could be produced on the SAM surface that were as densely packed as the underlying alkanethiolate SAMs comprising the first layer. The quality of the adsorbed monolayers was related to the identities of the tail groups X and Y.     

Immobilization of a Mo,V-polyoxometalate on cationically modified mesoporous silica: Synthesis and characterization studies

This paper presents studies on the immobilization of the polyoxometalate [PV₂Mo₁₀O₄₀]⁻⁵ (referred to as “POM”) on modified mesoporous MCM-41. The MCM-41 host material was made cationic by functionalization of the surface with [(MeO)₃Si(CH₂)₃N⁺(CH₃)₃]Cl. In polar solvents, POM is deprotonated and could be easily immobilized by wet impregnation of the modified silica using MeOH as the solvent. The physical properties of the samples were examined using XRD, FTIR, DR UV–Vis spectroscopy, ³¹P MAS-NMR, N₂ physisorption, and TEM. These techniques indicated that the POM is intact on the surface after impregnation. High loadings of POM caused a decrease in the surface area and pore volume of the solid, presumably due to both pore blockage and restructuring of the silica during wet impregnation. The texture and structure of the MCM-41 was studied as a function of POM loading.     

Effect of erucic acid on the rheological and surface properties of coal tar pitch

Coal tar pitch (CTP) was modified using erucic acid, CH₃(CH₂)₇CH=CH(CH₂)₁₁COOH, and the rheological and surface properties of the modified CTP were evaluated. The effect of erucic acid was investigated using a rotational viscometer as well as by drop and weight tests. The modified CTPs were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy following a carbonization process. The results showed significant differences in several properties between the CTP and modified CTPs, such as decreases in viscosity, wetting temperature, and softening point when erucic acid content was 1–3 wt% of CTP. An improvement in bonding between the coke and the modified CTP can be achieved when the coke value remained 62%. Moreover, a modification mechanism was proposed to explain the physical plastification of CTP modified with erucic acid.     

Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.