Preparation and Surface Activities of Modified Double-Tailed Anionic Surfactants

We prepared a series of modified double-tailed surfactants containing two identical nonionic moieties and an anionic spacer group. Each surfactant was prepared through the reaction of two moles of polyoxyethylene alkyl ether with one mole of maleic anhydride to form a diester having a gemini structure; an anionic sulfonate group was then introduced through reaction of the olefinic bond with sodium hydrogen sulfite. The structures of these compounds were confirmed through infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis. These modified double-tailed surfactants exhibit good surface properties, including low-foaming, wetting and lime-soap dispersing power. Their excellent dispersing abilities toward disperse dyes were due to the double-tailed structures of the surfactants, with the hydrophobic moieties increasing the binding ability to the dyes and its anionic units providing dispersing power.     

Synthesis and Surface Properties of a Novel Sodium 3‐(3‐Alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate at the Air–Water Interface

The present paper describes the synthesis and evaluation of surface properties of a novel series of anionic surfactant, namely sodium 3‐(3‐alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate with varying alkyl chain length (C8–C16). Synthesis involves initial formation of the 3‐alkyloxy‐3‐oxopropyl acrylate along with fatty acrylate during the direct esterification of fatty alcohol with acrylic acid in the presence of 0.5 % NaHSO₄ at 110 °C followed by sulfonation of the terminal double bond of the 3‐alkyloxy‐3‐oxopropyl acrylate. Synthesized compounds were evaluated for surface and thermodynamic properties such as critical micelle concentration (CMC), surface tension at CMC (γ_cmc), efficiency of surface adsorption (pC₂₀), surface excess (Γ_max), minimum area per molecule at the air–water interface (A_min), free energy of adsorption (?G°_ads), free energy of micellization (?G°_mic), wetting time, emulsifying properties, foaming power and calcium tolerance. Effect of chain length on CMC follows the classic trend, i.e. decrease in CMC with the increase in alkyl chain length. High pC₂₀ (>3) value indicates higher hydrophobic character of the surfactant. These surfactants showed very poor wetting time and calcium tolerance, but exhibited good emulsion stability and excellent foamability. Foaming power and foam stability of C14‐sulfonate were found to be the best among the studied compounds. Foam stability of C14‐sulfonate was also studied at different concentrations over time and excellent foam stability was obtained at a concentration of 0.075 %. Thus this novel class of surfactant may find applications as foam boosters in combination with other suitable surfactants.     

Preparation and surface activity of biodegradable polymeric surfactants. I. Preparation and surface activity of dextrin derivatives

Novel dextrin derivative surfactants containing a modified glucoside structure have been prepared in which propylene glycol polyglucosides are reacted with a hydrophobic oxirane‐containing material of glycidyl ether with C10–C18 carbon atoms. These surfactants exhibit good surface activities, including surface tension, low foaming, and wetting power. These surfactants also have a good ability to improve the whiteness and wetting power of cotton fabrics in a hydrogen oxide bleaching system. The benefits of these dextrin derivative surfactants are their highly biodegradable properties, which are lacking in traditional surfactants.     

Analysis of the wetting behaviour of pigments and the effectiveness of surfactants

A new test method is introduced to analyse the wetting behaviour of pigments and the effectiveness of surfactants. The method involves the study of torque vs time curves obtained during the wetting of pigments by surfactant solutions. These curves provide valuable information regarding the wetting behaviour of pigments and the ability of the surfactant to wet the pigment. To study the wetting behaviour, two pigments which varied widely in their surface character are studied with the same surfactant, while, to study the effectiveness of the surfactant, different surfactants with differing polarity are studied using the same pigment. The results are found to be consistent with the theoretical expectations.     

Preparation and surface activity of modified soy protein

A series of novel surfactants have been prepared by the reaction of hydrolyzed soy protein with alkyl succinic anhydride. These novel surfactants exhibit excellent surface active properties including surface tension, foaming, emulsifying, wetting power, and buffer ability. The hydrophobic modified protein exhibit more surface activity than original protein because of the enhanced hydrophobicity in structure. The increase in hydrophobic chain length leads to an increase in the surface activity. The surface tension reduction is correlated to the hydrophobicity of the modified molecule, which was determined by a fluorescent probe. In application on cotton bleaching procedures, these surfactants increase the whiteness of fabrics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3498–3503, 2006     

Capillary wetting rates in nylon fibrous assemblies

The capillary wetting rates in nylon fibrous assemblies were evaluated from the change in electrical conductivity due to wetting. The wetting liquids used were aqueous potassium chloride solutions of various pHs, in both the absence and the presence of ionic surfactants. Sodium dodecyl sulfate and dodecyltrimethylammonium chloride were chosen as surfactants. The contact angles of the wetting liquids on the nylon fiber were measured by the Wilhelmy method and the isoelectric point of the fiber was determined from electrokinetic data. The minimum wetting rate and the maximum contact angle were observed near pH 4, which coincided with the isoelectric point of the nylon fiber. In the presence of surfactant ions, the minimum wetting rate was also obtained at the concentration where the surface charge of nylon was neutralized. These experimental findings indicate that the capillary wetting rates in nylon fibrous assemblies are influenced by the electrical phenomena at the nylon/ solution interfaces via the contact angle and the structure of the adsorbed surfactant layers.     

Synthesis and Properties of Dissymmetric Gemini Surfactants

A series of novel dissymmetric gemini cationics surfactants was synthesized by three-step reactions. The dissymmetric gemini surfactants contain a dodecanoic acid dimethylethylamine ester as the constant cationic part on one side of the hydroxypropyl center and a similar other cationic part, but with a different acid length (from octanoic to palmitic), on the other side. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction (γ _CMC) were determined. The surface tension measurements of dissymmetric gemini surfactants showed good water solubility, and low CMC had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface. The CMC was observed to increase initially with the increase of the ester bond alkyl group. They also showed good foaming properties and wetting capabilites.     

Adsorption, Desorption and Adsolubilization Properties of Mixed Anionic Extended Surfactants and a Cationic Surfactant

Anionic and cationic surfactant mixtures exhibit desirable synergism, but are limited by their tendency to form precipitates. This research evaluates the adsorption, adsolubilization and desorption of mixtures of carboxylate-based anionic extended surfactants and a pyridinium-based cationic surfactant. The mixture of cetylpyridinium chloride (CPC), selected as the cationic surfactant, with four anionic extended surfactants were studied. The anionic surfactants studied were alkyl propoxylated ethoxylated carboxylate with average number of carbon chain length of 16 and 17 or 16 and 18 with 4?mol of propylene oxide groups and either 2 or 5?mol of ethylene oxide groups. The adsorption of anionic extended and cationic surfactant mixtures onto a negatively charged metal oxide surface (silica dioxide) was evaluated. The adsolubilization of phenylethanol, styrene and ethylcyclohexane were evaluated for these mixed surfactant systems. The desorption potential of individual and mixed surfactant systems was also evaluated by varying the number of washing (desorption) steps. It was found that the plateau adsorption of mixed anionic extended surfactant and cationic surfactant occurred at lower surfactant concentration than that of the CPC alone, although the maximum adsorption capacity of CPC was not enhanced in our mixed surfactant systems. Adsolubilization capacities of these mixed surfactant systems are higher than that of the individual surfactant system. For desorption studies, these mixed surfactant systems showed lower stability than the individual surfactant system.     

Synthesis and surface measurements of surfactants derived from dehydroabietic acid

Dehydroabietates with poly(ethylene oxide) chains of average m=12, 17, and 45 units [DeHab(E) _m ] were synthesized. The adsorption at the liquid-vapor interface was measured, and the adsorbed amount and critical micelle concentrations (CMC) were determined. The foamability, the foam stability, wetting properties, and cloud points, with and without salt content, were studied. The results were compared with common linear alkyl ethoxylates, nonylphenol ethoxylates, and cholesterol ethoxylates. The dehydroabietic acid as hydrophobe was found to result in the same CMC as a linear dodecyl chain. DeHab(E)₄₅ was found to be insoluble above 400 mg/L, but the surface tensions at lower concentrations were similar to those of the C_11–13E_38–40 surfactants, which exhibit CMC in aqueous media. The foaming behavior of the DeHab(E)₁₂ and DeHab(E)₁₇ surfactants was about the same as for common linear C _n E _m surfactants. The foamability as well as the foam stability increased with ethylene oxide (EO) chain length. The cloud point was depressed by increased salt concentration and increased with the number of EO units in the head group. The cloud point was significantly lower than for the corresponding surfactant with a dodecyl chain with similar EO chain length. The wetting results, obtained by measuring the contact angle at similar surface tensions, indicate that surfactants of the DeHab(E) _m type are more efficient wetting agents than both disaccharide sugar surfactants and C _n E _m type surfactants.     

Ortho ester-based cleavable cationic surfactants

A new type of cleavable cationic surfactant, based on the ortho ester link, is described. Ortho ester amines with alkyl chain lengths from C₈ to C₁₆ were synthesized from a short-chain ortho ester, a fatty alcohol, and an amino acohol. The ortho ester amine was subsequently quaternized with methyl chloride, yielding a cationic surfactant. The structures were confirmed by ¹H and ¹³C nuclear magnetic resonance and the surface chemical properties were investigated by measuring both static and dynamic surface tensions. The results were compared to standard n-alkyl trimethyl ammonium bromides. The critical micelle concentrations were found to vary rather widely, whereas the surface tensions in some cases were comparatively low. The short alkyl chain ortho ester quaternaries were found to have low surface tensions at short surface ages and to induce rapid wetting of a hydrophobic surface in dynamic tests. Additionally, the new surfactants were found to hydrolyze rapidly under mild acidic conditions, as measured by both titation and monitoring of the dynamic surface tension. Further, they showed excellent long-term stability at pH 10 in dilute aqueous solutions. The effect of added electrolyte on rate of hydrolysis was also investigated. A marked enhancement in the hydrolysis rate was found when NaBr was added, whereas NaCl did not have the same effect. The new surfactants could potentially be used to provide temporary surfactant action in application areas such as disinfection, fabric care, personal care, chain lubrication, and mineral flotation as well as in textile processes such as dyeing or scouring.     

Contrasts in the surface activity of polyoxypropylene and polyoxybutylene-based block copolymer surfactants

Previous studies have shown that polyoxybutylene surfactant hydrophobes are less polar than polyoxypropylene hydrophobes. Polyoxyalkylene hydrophobes can be modified by ethoxylation to give terminal polyoxyethylene block hydrophilic groups. Polyoxybutylene/polyoxyethylene copolymer surfactants exhibit differentiated interfacial tensions, and wetting and foaming properties when compared to structurally equivalent polyoxypropylene/polyoxyethylene copolymers. There have been no reported comparisons, however, of polyoxybutylene/polyoxyethylene copolymers and polyoxypropylene/polyoxyethylene analogues in terms of fundamental parameters, such as critical micelle concentration, area per molecule at the interface, efficiency, and effectiveness. In one phase of this work, four polyoxybutylene/polyoxyethylene block copolymer surfactants were compared to structurally analogous polyoxypropylene/polyoxyethylene materials. Findings showed that polyoxybutylene/polyoxyethylene copolymers exhibited enhanced cotton wetting and lower surface and interfacial tensions compared to polyoxypropylene/polyoxyethylene analogues. Polyoxybutylene-based surfactants were typically one order of magnitude better in their ability to reduce surface tension at interface saturation. Polyoxybutylene/polyoxyethylene copolymers pack more efficiently at the interface, as evidenced by a smaller area per molecule at the interface. Critical micelle concentration values were also lower for polyoxybutylene/polyoxyethylene copolymers. A second phase of experiments focused on the surface activity of polyoxypropylene/polyoxyethylene triblock copolymers with higher molecular weight hydrophobes. Enhanced surface activity was found when compared to lower-molecular weight polyoxypropylene/polyoxyethylene copolymers.     

Wettability modification of lignite by adsorption of alkyltrimethylammonium bromides with different alkyl chain length

To overcome the problem of moisture re-adsorption of dried lignite with common evaporation drying methods, a set of linear alkyl quaternary ammonium surfactants (C₁₀TAB, C₁₂TAB, and C₁₆TAB) were used to modify lignite surface, and the effects of alkyl chain length on the adsorption characteristics of surfactants and wettability of lignite surface were evaluated. Pseudo-first and pseudo-second-order kinetic models and Langmuir model were, respectively, used to simulate adsorption kinetics and adsorption isotherms. The results showed that three surfactants gradually formed double-layer adsorption on lignite surface and the loading of surfactant increased with the length of alkyl chain. X-ray photoelectron spectroscopy analysis showed that C₃H₉N⁺ moiety of the surfactants would preferentially interact with O?C?O groups of lignite. Results of wetting heating and moisture re-adsorption showed that three surfactants obviously decreased hydrophilicity and restrained moisture re-adsorption of lignite, but with the formation of double-layer adsorption, hydrophilic headgroups of surfactant faced outward, which caused increase in hydrophilicity of lignite. As a result of two opposite effects of surfactant chain length on lignite wettability, the effect of C₁₂TAB on decreasing hydrophilicity was the best among the three chosen surfactants.     

阳-阴离子表面活性剂复配对褐煤疏水改性效果的研究

对不同配比下阳离子表面活性剂十二烷基三甲基溴化铵(DTAB)和阴离子表面活性剂十二烷基磺酸钠(SDS)复配溶液的性质进行了测量与计算,并测定了褐煤吸附复配表面活性剂后的润湿热值、水分复吸率值、红外光谱和Zeta电位值。结果表明:复配表面活性剂在降低表面张力的效能和效率方面均表现出协同作用,且通过润湿热值和水分复吸率值可以看出,对比单一表面活性剂,褐煤吸附复配表面活性剂后润湿热值与水分复吸率值都有明显的降低;通过红外光谱和Zeta电位值证明了复配表面活性剂对褐煤的作用效果和方式。表面活性剂复配体系相比相应的单一表面活性剂对于褐煤的疏水改性效果表现出明显的协同作用。     

羟基和酯基型Gemini双季铵盐表面活性剂在煤沥青表面的润湿特性

以自制的羟基和酯基型Gemini双季铵盐表面活性剂为研究对象,在考察其表面活性的基础上,进一步研究了表面活性剂在煤沥青表面的润湿性。研究表明,羟基型Gemini表面活性剂在煤沥青表面的接触角随疏水链长度的增长呈先减小后增大趋势,其中C₁₂-OH在煤沥青表面的润湿效果最好;对于m-n-m酯基型Gemini表面活性剂而言,接触角随疏水链长度的增长而降低。当疏水链长度一定时,m-6-m在煤沥青表面的润湿效果比m-2-m好。在一定浓度范围内,C₁₀-OH、C₁₂-OH和12-2-123种Gemini表面活性剂的表面张力与其在煤沥青表面黏附张力呈线性关系。煤沥青表面的Zeta电位随Gemini表面活性剂浓度的增大呈先增大后趋于平稳的趋势。     

Preparation and Properties of New Ester-Linked Cleavable Gemini Surfactants

We have prepared a series of novel gemini surfactants having ester bonds in their structures. These surfactants possess two identical hydrophilic polyethylene glycol moieties, two hydrophobic alkyl group moieties, and an anionic spacer. The structures of these compounds were confirmed through infrared and nuclear magnetic resonance spectroscopic and elemental analyses. The novel gemini surfactants exhibit excellent surface activity in terms of their surface tension, low-foaming, wetting power, and fluorescence properties. The presence of the ester linkages made these structures cleavable surfactants.     

Synthesis and evaluation of micellar properties and antimicrobial activities of imidazole‐based surfactants

The synthesis of two types of imidazole‐based surfactants, [(ROCOCH₂MIm)Br] and [(RNHCOCH₂MIm)Br], of varying chain lengths (C₁₀, C₁₂ and C₁₆), was conducted in the present work. The synthesis involves an initial reaction of bromoacetic acid with fatty alcohols or fatty amines, followed by quaternization with N‐methyl imidazole. The micellar properties of all the synthesized compounds were determined using surface tensiometry and compared with [(RMIm)Br], a well‐studied alkyl‐substituted imidazole‐based surfactant. Within the same homologous series, a decrease in critical micelle concentration (cmc) was observed with increasing alkyl chain length in all three types of cationic surfactants. Introduction of an ester [(ROCOCH₂MIm)Br] or an amide group [(RNHCOCH₂MIm)Br] in the alkyl chain lowers the cmc when compared to a cationic surfactant without functional group, [(RMIm)Br]. The synthesized surfactants were also assayed for antimicrobial activities and found to possess good activities against selected strains.     

Syntheses of sodium 2-(N-alkyl-N-methylamino)ethanephosphates and their physicochemical properties

A series of new amphoteric surfactants, sodium salts of 2-(N-alkyl-N-methylamino)ethanephosphates (alkyl: n-dodecyl, n-tetradecyl and n-hexadecyl) were prepared by reacting alkylbromides with N-methylaminoethanol, followed by addition of phosphoric acid groups and neutralization with sodium hydroxide. The structures of these compounds were confirmed by spectroscopy and elemental analysis. Physical properties such as Krafft point, isoelectric point, critical micelle concentration, occupation area of molecule at surface, foaming power and the effect of pH on surface activity were evaluated. These surfactants were found to exhibit zwitterionic characteristics in the pH range from approximately 5 to 9 and demonstrated good surface-active properties over a wide pH range (pH 4~10). Large occupation areas of the molecule at a surface in comparison with sodium dodecyl sulfate was noted as a characteristic feature of these surfactants.     

Influence of Ionic Surfactants on the Formation of Liquid Crystals in Oleic Acid/Glycol/Water Systems

The influence of surfactant structure on the formation of lamellar liquid crystals with very low surfactant concentration was investigated for systems composed of oleic acid, diethyleneglycol ethyl ether and water. Surfactants belonging to anionic and cationic families were checked: phosphated oleyl ether 3 EO (PO₃EO), triethanolamine oleate (TEAO) and sodium lauryl ether sulphate (SLES) as anionic surfactants and two alkyl trimethylammonium bromide type (C₁₂TAB and C₁₄TAB) as cationic surfactants. For each of the surfactants, the appropriate relationships between surfactant, oleic acid and glycol to furnish lamellar liquid crystals when these basic compositions were further diluted with water were established. The appropriate ranges of dilution allowing the liquid crystal formation were also determined. These liquid crystals presented an attractive appearance because of their transparency and high viscosity, although in the beginning of its formation, a short range of less viscous compositions (so called liquid/gel compositions) appears in some cases. Through water dilution, the initial surfactant percentages are noticeably reduced being possible liquid crystals with 2–5 wt% of surfactant.

Self-Assembly of Polyethylene Glycol Ether Surfactants in Aqueous Solutions: The Effect of Linker between Alkyl and Ethoxylate

The aqueous self-assembly behavior of two homologous series of poly(ethylene oxide) (PEO)-containing nonionic surfactants based on a C₁₀-Guerbet hydrophobe is reported. The two families of surfactants, alkyl ethoxylates and alkyl alkoxylates, are commercially available from BASF under the trade name Lutensol® XP-series and XL-series, respectively. The latter incorporate propylene oxide (PO) units in the surfactant chain. Dye solubilization was used to determine the critical micellization concentration (CMC) of each surfactant at 22 and 50 °C. The PO-containing alkyl alkoxylates displayed lower CMC values, which were also more sensitive to temperature. The Gibbs free energy, enthalpy, and entropy of micellization were computed from the CMC data and used to identify the contribution of each surfactant moiety (alkyl chain, PO unit, and PEO block) in controlling the CMC. The micellization properties are compared with compositionally similar surfactants with linear alkyl chains, yielding information about the effects of the Guerbet alkyl chain on micellization. Isothermal titration calorimetry was also used to characterize the CMC and enthalpy of micellization which generally compare well with the dye solubilization results. Cloud point data reveal nonmonotonic relationships for the Lutensol® surfactants with respect to composition, unlike linear alkyl chain surfactants. Finally, dilute solution viscosity measurements performed on some Lutensol® surfactants show a change in the slope, suggesting a structural change that tends to be more pronounced for surfactants with longer PEO blocks. The data presented herein enhance the understanding of surfactant structure–property relationships required for industrial formulation.