Surface and thermodynamic studies of N-alkkyl N-trimethylsilane ammonium chloride surfactants

N-Dodecyl N-trimethylsilane ammonium chloride, N-tetradecyl-N-trimethylsilane ammonium chloride, N-hexadecyl-N-trimethylsilane ammonium chloride, and N-octadecyl-N-trimethylsilane ammonium chloride were prepared. Surface properties, particularly critical micelle concentration (CMC), effectiveness, maximum surface excess, and minimal surface area, were determined at different concentrations at 20, 35, 50, and 65°C, respectively. From electrical conductivity data, degrees of dissociation and dissociation constants at various concentrations were determined. Free energies, enthalpies, and entropies of micellization and adsorption of the surfactants in aqueous solution were studied.     

Synthesis and surface properties of N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine-N-oxides

A new group of saccharide surfactants, N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine-N-oxides (derivatives of d-gluconic, d-glucoheptonic, and lactobionic acids), were synthesized with high yields by one-step oxidation reaction of an appropriate N-dodecyl-N,N-bis[3-(aldonamido)-propyl]amine with an excess of 30 wt% of an aqueous solution of hydrogen peroxide. Their structures and purity were confirmed by means of elemental analysis, electrospray ionization mass spectrometry, and ¹H and ¹³C nuclear magnetic resonance spectroscopy. In comparison to an appropriate N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine, the investigated N-oxides are more soluble in water with similar critical micelle concentration values and show higher surface effectiveness. They are low-foamable but in mixtures with sodium dodecyl sulfate form high-volume and stable foams in a wide range of mixture compositions.     

Synthesis and surface properties of new dicephalic saccharide-derived surfactants

A new group of nonionic dicephalic saccharide amides, N-dodecyl-N,N-bis[(3-d-gluconylamido)propyl]-amine, N-dodecyl-N,N-bis[(3-d-glucoheptonylamido)propyl]-amine, and N-alkyl-N,N-bis[(3-lactobionylamido)propyl]amines (alkyl: n-C₁₂H_25′ n-C₁₆H_33′, n-C₁₈H₃₇) were synthesized and characterized. Their structure and purity were confirmed by means of ¹H and ¹³C nuclear magnetic resonance analysis and electrospray ionization mass spectrometry. Carbon spectra were verified using a DEPT experiment. The surface and interfacial properties such as critical micelle concentration (CMC), standard free energy of micellization, ΔG _CMC, surface excess concentration, Γ_CMC, and surface area demand per molecule, A _CMC, were determined. The tertiary nitrogen atom seems to have a surprising effect on surfactnat packing at the interface.     

Effect of urea and salt on micelle formation of zwitterionic surfactants

The effect of urea on micelle formation of zwitterionic surfactants was investigated by measuring conductivity, critical micelle concentration (CMC), relative viscosity, and the spectrophotometric shift in wavelength. We examined two zwitterionic surfactants, N,N-dimethyl dodecylamine N-oxide and N,N-dimethyl tetradecylamine N-oxide (DMTAO). The CMC values of the surfactants increased with the addition of urea. Also, the relative viscosity of the surfactant solutions decreased at higher concentrations of urea and increased with increasing KCl concentration. The absorbance maxima of the surfactants decreased with increasing urea concentration.     

Investigations on the growth ofRhodococcus rubra in relation to the formation of stable biological foams

The growth characteristics of a foam-forming species,Rhodococcus rubra were studied on different substrates. The basic medium contained Czapek (3.34%), yeast extract (0.2%), potassium dihydrogen phosphate (0.12%), dipotassium hydrogen phosphate (0.25%) and ammonium chloride (0.1%). This was supplemented with varying concentrations of glucose (0–2%). The same basic medium was also used to examine the growth ofR. rubra in combination with varying concentration of n-hexadecane (0.0–0.5%) as a source of energy while varying the concentration of ammonium chloride in the range 1–3 gl ⁻¹. Studies based on determining the biomass concentration, the surface activity related to the cell suspensions and measuring the variations in broth pH revealed that glucose encouraged the growth ofR. rubra, compared to the control. However, increasing the glucose concentration from 0.1 to 2.0% had no further effect on growth. The surface activity of the cell suspensions increased with increasing glucose concentration. Results similar to glucose were exhibited by the addition of n-hexadecane, suggesting same degree of growth among different concentrations with higher surface activity increasing with increase in substrate concentration. Results have also shown that the pH of all the culture broths decreased as the ammonium chloride concentration increased, suggesting that there was a production of hydrogen ions during the course of its metabolism.     

Environmentally acceptable drag-reducing surfactants for district heating and cooling

The aim of this work was to find drag-reducing surfactants for both district heating and cooling that are environmentally more acceptable than the organic salts of quaternary ammonium compounds that so far have dominated this application. Vortex inhibition of test solutions in glass beakers has been used to screen a large number of surfactant mixtures, various electrolytes, and temperatures. For the most interesting products, the pressure drop in a test loop was measured at various flow rates and temperatures.N-cetyl sarcosinate andN-stearyl betaine, the latter together with Na-dodecylbenzene sulfonate, give good drag reduction (DR) properties at 65–100 and 45–85°C, respectively. The sarcosinate is sensitive to pH changes, whereas the betaine-sulfonate complex is more robust. Ethoxylates of oleic acid monoethanolamide show good DR properties at 0–25°C. At an increased salt concentration, a mixture of this surfactant with an ethoxylated oleyl alcohol worked well. At a still higher salt concentration, e.g., sea water, a combination ofN-cetyl betaine and alkylbenzene sulfonate showed DR.     

Surface Properties and Biological Activity of Select Cationic Surfactants

A series of cationic surfactants, N-(decyl N-tri-ethanol ammonium Bromide) (C₁₀), N-(dodecyl N-triethanol ammonium Bromide) (C₁₂), N-(hexadecyl N-triethanol ammonium Bromide) (C₁₆) were synthesized. These compounds have been evaluated by studying their surface properties, surface parameters, biodegradability and antimicrobial and antifungal activities.

Corrosion inhibition by N‐(alkyloxycarbonylmethyl)‐N‐triethanol ammonium chloride with respect to the surface and thermodynamic properties

N‐[(octyloxycarbonylmethyl)‐ N‐triethanol ammonium chloride] (C₈ ), N ‐[(dodecyl‐oxycarbonylmethyl)‐ N‐triethanol ammonium chloride] (C₁₂ ) and N ‐[(hexadecyloxycarbonylmethyl)‐N ‐triethanol ammonium chloride] (C₁₆ ) were synthesized. Surface tension was measured in aqueous solution for different concentrations at 28, 38 and 48°C. Various surface properties of the synthesized surfactants were evaluated, particularly critical micelle concentration (CMC), efficiency (Π_CMC) as well as maximum surface excess (Γ_max) and minimum surface area (A_min). Micellization and adsorption in both liquid/air and liquid/solid interfaces thermodynamics were investigated. These products have pronounced surface activity and satisfactory corrosion inhibition of C‐steel in hydrochloric acid at 28, 38 and 48°C. © 1999 Society of Chemical Industry     

Adsorption of Bovine Serum Albumine Onto Poly (<Emphasis Type="Italic">N</Emphasis>-<Emphasis Type="Italic">t</Emphasis>-Butylacrylamide-co-Acrylamide/Maleic Acid) Hydrogels

In the present study, a series of ionic poly(N-t-butylacrylamide-co-acrylamide) [P(NTBA-co-AAm)] hydrogels were synthesized by free-radical crosslinking copolymerization of N-t-butylacrylamide (NTBA) and acrylamide (AAm) monomers in fixed amount, but changing amount of maleic acid (MA) comonomer in methanol using N,N-methylene-bis-acrylamide (BAAm) as the crosslinker, ammonium persulfate (APS) as the initiator, and N,N,N′,N′-tetramethylethylenediamine (TEMED) as the activator. The swelling behavior of these hydrogels was analyzed in buffer solutions at various pHs. The prepared hydrogels also were investigated swelling-deswelling transition in water depending on the temperature. For the bovine serum albumin (BSA) adsorption, the effect of pH, temperature, initial protein concentration and adsorption rate were investigated. Maximum BSA adsorption was observed at pH 5.0 which is close to the isoelectric pH of BSA (pH 4.8). The highest adsorption rate was achieved in about 12 h. and also, maximum BSA adsorption was found at +5°C.     

Synthesis and Properties of 1,1-bis{[3-(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)propyl]amido}alkane-di-<Emphasis Type="Italic">N</Emphasis>-oxides

A homologous series of new surface-active 1,1-bis{[3-(N,N-dimethylamino)propyl]amido}alkane-di-N-oxides were synthesized in the reaction of an appropriate diethyl 2-alkylmalonate with N,N-dimethylamino-1,3-propanediamine followed by oxidation with aqueous hydrogen peroxide. The adsorption isotherms of their aqueous solutions were measured and evaluated to obtain adsorption parameters: critical micelle concentration (CMC), surface excess concentration (Γ_CMC), equilibrium surface tension at the CMC (γ_CMC), cross-sectional area of the adsorbed surfactant molecule (A _CMC), efficiency of surface adsorption (pC₂₀), standard free energies of adsorption (ΔG°_ads), and micellization (ΔG°_CMC). All investigated di-amidoamines and di-N-oxides were practically non-toxic to selected bacteria and yeasts. These compounds are readily biodegradable in the Closed Bottle Test inoculated with activated sludge. Surface and biological properties showed that this group of N-oxide-type compounds has high surface activity and fulfills requirements for environmental acceptance.

Synthesis and Properties of Surface Chemically Pure Alkylamidoamine-N-oxides at the Air/Water Interface

A homologous series of surface active 2-(alkanoylamino)ethyldimethylamine-N-oxides, EDA-p(O), and 3-(alkanoylamino)propyldimethylamine-N-oxides, PDA-p(O), were synthesized. Their aqueous stock solutions were processed by the automatically operating apparatus to remove surface-active contamination and provide chemical purity at the air/water interface. In case of 3-(tetradecanoylamino)propyldimethylamine-N-oxide, PDA-14(O), the difference between equilibrium surface tension values of the purified surfactant solutions and the corresponding values of the solutions prepared from the “as received” compounds amounts to 15 mN m⁻¹. Moreover, in presence of the surface-active contaminants time needed to reach equilibrium surface tension values is over 2 h. For the solution of the “surface-chemically pure” grade the change of the surface tension within adsorption time is negligible and the equilibrium is reached instantaneously. Physicochemical properties of obtained surface-chemically pure aqueous solutions of N-oxides of alkylamidoamines and adsorption parameters (standard free energy of adsorption, ΔG°_ads, surface excess by saturation surface concentration, Γ_∞, minimum surface area demand per molecule adsorbed, A _min) were evaluated from the equilibrium surface tension versus concentration isotherms at the air/water interface using Gibbs’s equation. The introduction of the CH₂ moiety into the intermediate part of molecule causes a slight decrease of the hydrophobic character of surfactant. Also the minimum surface area demand, A _min, is slightly greater for PDA series than for the corresponding EDA derivatives. Surface potential measurements were performed in addition to surface tension studies. Electric surface potential versus concentration isotherms was determined. Surface potential increases with increasing surfactant’s bulk concentration for all investigated compounds. At highest concentrations, where interface is almost saturated, changes of surface potential become almost negligible.

Synthesis,characterization and antibacterial activity of quaternized <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-(2-carboxyethyl) chitosan

N,O-(2-carboxyethyl)chitosan (N,O-2-CEC) was prepared from chitosan with 3-chloropropionic acid as modifying agent and NaOH as catalyst. Different quaternary ammonium groups were introduced into N,O-2-CEC by the reaction between N,O-2-CEC and different 2,3-epoxypropyl trialkyl ammonium chlorides in the presence of 25% NaOH aqueous solution, and obtained different quaternized N,O-2-carboxyethyl chitosans (QCECs). Structures of QCECs were characterized by FT-IR, ¹HNMR and gel permeation chromatography (GPC). Antimicrobial activity of QCECs was evaluated against a gram-negative bacterium Escherichia coli and a gram-positive bacterium Staphylococcus aureus. Compared with N,O-2-CEC and quaternized chitosans, the QCECs had much stronger antimicrobial activity, which increased with increasing chain length of the alkyl in the quaternary ammonium groups. The presence of benzyl in quaternary ammonium groups could endow QCECs with much better antimicrobial activity.     

Preparation and properties of new lactose-based surfactants

A new group of nonionic saccharide-based surfactants, N-alkanoyl-N-methyllactitolamines (alkanoyl: decanoyl, lauroyl, myristoyl, palmitoyl, stearoyl), were synthesized and characterized. Surface properties such as critical micelle concentration, standard free energy of adsorption, standard free energy of micellization, surface tension reduction efficiency, effectiveness of surface tension reduction, surface excess concentration, and surface area demand per molecule as well as foaming properties (i.e., foam volume and foam stability), contact angle, antiraicrobial activity, and biodegradability were determined. The selected performance properties were evaluated in relation to commercially available alkyl polyglucosides (Glukopon 600 EC(HH)-a Henkel product), and oligooxyethylenated decyl (C₁₀E₄) and dodecyl (E₁₂E₅) alcohols. The foaming-stabilizing effect and contact angle suggest that the lactose-derived surfactants that were studied share some common properties with alkyl polyglucosides that are different from those with an oligooxyethylene grouping. All tested N-alkanoyl-N-methyllactitolamines were practically nontoxic to bacteria and yeasts. These compounds are readily biodegradable in the Closed Bottle test inoculated with activated sludge. N-Alkanoyl-N-methyllactitolamines with lower chain lengths (C₁₀–C₁₄) biodegraded at a slightly faster rate. Biological properties showed that this class of compounds fulfills all requirements needed for environmental acceptance.     

Adsorption of Novel Alkylaminoamide Sugar Surfactants at Tailor-made Surfaces

N,N-di(3-aminopropyl)dodecylamine (C12-Y-amine), N-dodecyl-N,N-di[(3-d-gluconylamido)propyl]amine (C12-DGA), N-dodecyl-N,N-bis[(3-lactobionylamido)propyl]amine (C12-DLA), N-dodecyl-N-[(3-lactobionylamido)propyl]amine (C12-LA), and ethoxylated N,N-di(3-aminopropyl)dodecylamine [C12-Y-amine with 4 and 8 ethylene oxide (EO)] have been synthesized, and their physical-chemical properties have been studied. Adsorption was measured at the air–water interface by the du Noüy ring method and at solid surfaces consisting of self-assembled monolayers (SAMs) of alkanethiols on gold using surface plasmon resonance. Results from surface tension measurements showed that adsorption at the air–water interface is pH dependent. At low pH, reduction in surface tension is less pronounced as a result of protonation of the amino groups of the surfactants. At the SAM model surfaces, generated by adsorption of alkanethiols or mixtures of alkanethiols on gold presenting methyl, hydroxyl, and carboxyl groups, the highest amount of adsorbed surfactant was obtained on a surface composed of a mixture of methyl and carboxyl groups. In general, the sugar-derived surfactants, DGA, DLA, and LA, adsorbed less than the ethoxylates. Surfactant biodegradation was investigated by the closed bottle test. Only C12-Y-amine was found to be readily biodegradable. However, the polyol surfactants were more biodegradable than the ethoxylates.

Synthesis and Properties of Functionalized Alkylaldonamides

Application studies of novel saccharide-type nonionic surfactants were performed. The homolog series of N-alkyl-N-(2-hydroxyethyl)gluconamides and N-alkyl-N-(2-hydroxyethyl)glucoheptonamides (alkyl: n-C₁₀H₂₁, n-C₁₂H₂₅, and n-C₁₄H₂₉) were synthesized and their structures were confirmed by means of elemental analysis and ¹H-NMR spectroscopy. The investigations showed that the application of N-alkyl-N-(2-hydroxyethyl)aldonamides as surfactants in an aqueous media can be limited. This is because of their relatively high Krafft point temperature. However, some variants can be successfully applied in mixtures with an anionic surfactant: sodium salt of n-dodecyl sulfate (SDS). The addition of SDS causes significant improvement of the Krafft point temperatures. In some cases a synergistic effect was observed, i.e., the Krafft point temperature of the binary mixture was lower that the corresponding values for the solutions containing individual compounds. It is also remarkable, that the aqueous solutions of binary surfactant mixtures were characterized by improved foaming properties, as compared to that of pure SDS.

Synthesis and Surface Properties of Dicephalic Surfactants with a 1,3-Dioxane Ring

A new group of surface active dicephalic derivatives of 1,3-dioxane, i.e., 2-alkyl-5,5-bis{[3-(N,N-dimethylamino)propyl]amido}-1,3-dioxane-di-N-oxides, were synthesized with high yields by the reaction of an appropriate 2-alkyl-5,5-bis-(carboxyethyl)-1,3-dioxane with an excess of N,N-dimethyl-1,3-propanediamine followed by oxidation with an aqueous solution of hydrogen peroxide. Structures and purity of all intermediates and final di-N-oxides were confirmed by means of ¹H-NMR and ESI-MS spectroscopy. Synthesized compounds showed high surface activity with low values of critical micelle concentration and high effectiveness of surface tension reduction (γ _CMC). However, only derivative with the longest 2-alkyl substituent showed good foaming and moderate emulsifying properties.

Bifunctional N-Oxides of Alkyldiamidoamines

A homologous series of new surface-active 1,1-bis{[3-(N,N-dimethylamino)ethyl]-amido}alkane-di-N-oxides were synthesized in the reaction of an appropriate diethyl 2-alkylmalonate with N,N-dimethylethylenediamine followed by oxidation with an aqueous solution of hydrogen peroxide. The adsorption isotherms of their aqueous solutions were measured and evaluated to obtain adsorption parameters: critical micelle concentration (CMC), surface excess concentration (Γ_CMC), equilibrium surface tension at the CMC (γ _CMC), cross-sectional area of the adsorbed surfactant molecule (A _CMC), standard free energies of adsorption and micellization

Poly(urea-urethane) polymers with multi-functional properties

Polyurea-urethanes with multifunctional properties were synthesized by reacting 4,4′-diphenylmethane disocyanate (MDI) with a two diol mixture of polytetramethylene glycol (PTMG (1000, 2000) and biocidal quaternary ammonium monomer ((N-benzyl-N-dodecyl-N-bis2-hydroxyethyl) ammonium chloride (BDAC)), and extended with N-(2-hydroxyethyl) ethylene diamine (HEDA) to form PU polymers. The PU polymer was then grafted with a disperse dye via a coupling agent of epichlorohydrin to form a dye grafted polyurethane with biocidal and covalent bond dyeing properties. In consideration of the mechanical properties, it is found that both the modulus and the strength of the dye grafted PU polymer films are lower than those of pure PU polymers due to the bulkiness of their dye molecules. For thermal properties, the dye grafted PU polymers exhibit higher T_gh than those without dye molecules. However,neither the T_gs nor the T_ms vary in the presence of BDAC or dye molecules, but they are changed with various chain lengths of the soft segment. For dyeing properties, the effective dyeing efficiency of dye grafted PU is over 85%. Moreover, the dye grafted PU polymers exhibit lower dye migration (M_p%) than those of simple mixtures of PU and dyestuff, and they show a higher grade of color fastness when exposed to light. In the shake method of antibacterial testing, the modified PU polymers exhibit a long lasting biocidal activity.     

Thermoreversible hydrogels VI: Swelling behavior of the (N-isopropylacrylamide-co-diethyl methyl methacryloyloxyethyl ammonium iodide) copolymeric hydrogels in aqueous salt solutions

A series of N-isopropylacrylamide/diethyl methyl methacryloyloxyethyl ammonium iodide (NIPAAm/DEMMAI) copolymeric gels were prepared from blending NIPAAm, cationic monomer DEMMAI, and N,N′-methylene bisacrylamide (NMBA) in various molar ratios in this article. The effects of the amount of the cationic monomer in the copolymeric gels on the swelling behaviors in water and various saline solutions at various temperatures were investigated. Results showed that the swelling ratios of copolymeric gels were significantly larger than those of pure NIPAAm gel, and that the more the DEMMAI content, the higher the gel transition temperature. In the saline solution, results showed that the swelling ratio for pure NIPAAm gel had not changed significantly with an increase of the salt concentration until the salt concentration was larger than 0.1 M. The swelling ratios for the copolymeric gels NIPAAm/DEMMAI were decreased with increasing salt concentration. In various saline solutions, results showed that the anionic effects were greater than cationic effects in the presence of common anion with different cations and common cation with different anions for these hydrogels. Finally, we also tested the reversibility of the NIPAAm/DEMMAI copolymeric gels. The deswelling and reswelling kinetics were dependent on the temperature which was below or above the gel transition temperature. The gel with a small DEMMAI content has a good reversibility.     

Cathodic reduction of 4-nitroso-N,N-dimethylaniline at various electrode materials

This study is concerned with the cathodic reduction of 4-nitroso-N,N-dimethylaniline to 4-amino-N,N-dimethylaniline in 1.0 M HCl and 1.0 M H₂SO₄ containing 10% MeOH. The effect of cathode material, supporting electrolyte, electroactive compound concentration, temperature and current density in the electrochemical synthesis of 4-amino-N,N-dimethylaniline were investigated. The best cathode material was tin, which gave a selectivity of 92.7% with a current yield of 90.3% at a current density of 6 mA cm^–2. The final electrolysis product was obtained as its respective HCl and H₂SO₄ salts and their structures were elucidated using spectrochemical techniques.