Styrene and Phenylethanol Adsolubilization of a Polymerizable Gemini Surfactant

A polymerizable gemini surfactant was used to adsolubilize styrene and phenylethanol, representing less and more polar organic solutes, respectively, in order to evaluate the impact of admicellar polymerization on the adsolubilization process. Adsolubilization was also evaluated using a polymerizable monomeric surfactant and conventional surfactant for comparison purposes. The main results were that: (1) polymerized and unpolymerized admicelles showed similar adsolubilization potential—validating the use of polymerized admicelles without sacrificing adsolubilization, and (2) gemini surfactants showed adsolubilization capacities equal to or higher than conventional surfactants.     

Ethoxy Carboxylate Extended Surfactant: Surface Charge of Surfactant-Modified Alumina, Adsolubilization and Solubilization of Phenylethanol and Styrene

Adsolubilization of contaminants by surfactant-modified material is an important phenomenon for surfactant-based environmental technologies. Recently, extended surfactants have been shown to enhance the adsolubilization capacity of organic solutes. In this study, two extended surfactants (ethoxy propoxylated carboxylate extended surfactant—C16PO4EO5C and propoxylate extended sulfate surfactant—C16PO4S) were selected for modifying positively charged alumina surfaces with the aim of enhancing adsolubilization of organic solutes with varying degrees of polarity (phenanthrene, styrene, and phenylethanol). The nature of the charged surface as a function of extended surfactant adsorption was evaluated through the zeta potential measurements. The results showed that at maximum bilayer coverage, the zeta potential of the alumina surface remained constant and was oppositely charged (negative) to the unmodified alumina (positive). Zeta potential measurements showed that the adsorbed bilayer of carboxylate-based extended surfactant produced more negatively charged surface. Surfactant desorption results showed that the surfactant-modified surface retained their negatively charge, albeit reduced, indicating that partial desorption occurred but not to the point that the positively charged alumina surface was realized. The adsolubilization results suggest a benefit of the ethoxy groups in adsolubilizing the polar phenylethanol in the palisade layer.     

Solubilization and Adsolubilization of Polar and Nonpolar Organic Solutes by Linker Molecules and Extended Surfactants

Adsolubilization reaches its maximum when a surfactant adsorbed onto the solid–liquid interface achieves complete bilayer or maximum adsorption. The attempt to enhance the adsolubilization of organic solute is accomplished by increasing interaction between the hydrophobic core of adsorbed admicelles and the organic solute. Solubilization and adsolubilization were studied with linker-based and extended-surfactant-based systems. Extended surfactants have propylene oxide (PO) groups of intermediate polarity inserted between hydrophobic and lipophilic moieties in the surfactant molecule. This study evaluated the adsolubilization of polar (phenylethanol) and nonpolar (ethylcyclohexane) solutes into conventional linker-based and extended-surfactant-based admicelles. The results demonstrated that the extended-surfactant-based systems showed higher solubilization capacity than the conventional sodium dodecyl sulfate alone or with linker. For the polar solute, the presence of PO group has a greater effect than the number of PO groups or the tail length, while for the nonpolar solute as the number of POs groups and the tail length increased, the adsolubilization capacity also increased. Preliminary explanations for these observations are provided.

Effect of Ionic Head Group on Admicelle Formation by Polymerizable Surfactants

One of the problems of using surfactant-modified adsorbents in a surfactant-based adsorption process is loss of surfactant because of desorption. Recently, polymerizable surfactants have been used to minimize surfactant losses by polymerization of the surfactant admicellar structure to help secure it to the solid oxide surface. In this study, adsorption of polymerizable cationic gemini surfactant was used to form polymerized bilayers on silica. UV light was used to irradiate and initiate the polymerization process. Surfactant adsorption and desorption were evaluated to compare the efficiency of polymerized and non-polymerized surfactants using gemini and conventional surfactants, respectively. Results demonstrate that the increased stability of the polymerized surfactant-modified surface can reduce the desorption of surfactant from the surface, thereby improving operating characteristics of the surfactant-modified media (e.g., maintaining adsolubilization potential, dispersion stability, etc.).     

The effect of cationic surfactants in acid cleaning solutions on protective performance and adhesion strength of the subsequent polyurethane coating

The subsequent effect of the use of monomeric cationic surfactants, dodecyltrimethylammonium bromide (DTAB) and its gemini counterpart, 12-4-12, in 1 M sulfamic acid cleaning solution on the corrosion resistance and adhesion strength of polyurethane coating on mild steel surface was studied by salt spray and pull off, respectively. The EIS (electrochemical impedance spectroscopy) was employed to evaluate the corrosion behavior of mild steel during the contact with sulfamic acid solutions. Inhibition performance of DTAB on mild steel at the initial period of immersion was somewhat higher than 12-4-12, while at prolonged immersion period 12-4-12 was more effective than DTAB. The higher protection and adhesion for the coating applied on the mild steel washed with DTAB solution was connected to more rapid adsorption for DTAB than 12-4-12 at short immersion period due to its small molecular weight which resulted in better mobility of DTAB molecules.     

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.     

Solubility of Two Disperse Dyes Derived from <Emphasis Type="Italic">N</Emphasis>-Alkyl and <Emphasis Type="Italic">N</Emphasis>-Carboxylic Acid Naphthalimides in the Presence of Gemini Cationic Surfactants

The solubility of naphthalimide-based monoazo dyes containing N-ethyl and N-ethanoic acid groups was investigated in the presence of a conventional monomeric counterpart (DTAB) and two cationic gemini surfactants (12-4-12 or 14-4-14) individually. The effective parameters on dye solubility such as temperature, time and concentration of surfactants were investigated by UV–Visible spectrophotometry. The results demonstrate that the solubility of both dyes was considerably increased at concentrations above the surfactant CMC. The wavelength for the maximum absorbance of dyes in the aqueous solution shifts toward longer wavelengths with changes in the concentration of the cationic surfactants. A kinetic study of solubilization of dyes in cationic surfactants solution showed that the rate of solubilization follows the pseudo-first-order reactions. Rates of solubilization were in the range of 0.5 × 10⁻³ to 6.8 × 10⁻³ min⁻¹ for both dyes. The disperse dye containing a carboxylic acid group (dye 2) has a higher solubility rate than the dye containing an alkyl group (dye 1). The type of surfactant has a very low effect on adsorption of dye 1 onto the polyester fibers, whereas changing the surfactant type from DTAB to 12-4-12 or 14-4-14 causes adsorption of dye 2 on polyester to decrease.     

Mixtures of anionic and cationic surfactants with single and twin head groups: Solubilization and adsolubilization of styrene and ethylcyclohexane

Mixtures of anionic and cationic surfactants with single and twin head groups were used to solubilized styrene and ethylcyclohexane into mixed micelles and adsolubilize them into mixed admicelles on silica and alumina surfaces. Two combinations of anionic and cationic surfactants were studied: (i) a single-head anionic surfactant, sodium dodecyl sulfate (SDS), with a twin-head cationic surfactant, pentamethyl-octadecyl-1,3-propane diammonium dichloride (PODD), and (ii) a twin-head anionic surfactant, sodium hexadecyl-diphenyloxide disulfonate (SHDPDS), with a single-head cationic surfactant, dodecylpyridinium chloride (DPCl). Mixtures of SDS/PODD showed solubilization synergism (increased oil solubilization capacity) when mixed at a molar ratio of 1∶3; however, the SHD-PDS/DPCl mixture at a ratio of 3∶1 did not show solubilization enhancement over SHDPDS alone. Adsolubilization studies of SDS/PODD (enriched in PODD) adsorbed on negatively charged silica and SHDPDS/DPCl adsorbed on positively charged alumina showed that while mixtures of anionic and cationic surfactants had little effect on the adsolubilization of styrene, the adsolubilization of ethylcyclohexane was greater in mixed SHPDS/DPCl systems than for SHDPDS alone. Finally, it was concluded that whereas mixing anionic and cationic surfactants with single and double head groups can improve the solubilization capacity of micelles or admicelles, the magnitude of the solubilization enhancement depends on the molecular structure of the surfactant and the ratio of anionic surfactant to cationic surfactant in the micelle or admicelle.     

Interfacial Dynamic Properties and Dilational Rheology of Sulfonate Gemini Surfactant and its Mixtures with Quaternary Ammonium Bromides at the Air–Water Interface

The dynamic interfacial properties and dilational rheology of gemini sulfonate surfactant (SGS) and its mixtures with quaternary ammonium bromides (DTAB, CTAB) at the air–water interface were investigated using drop shape analysis. Results suggest that the adsorption process of these surfactants is diffusion-controlled at dilute concentrations, whereas the adsorption mechanism gradually shifts to a mixed kinetic-diffusion control with increasing surfactant concentration. The mixed surfactant system possesses the best surface activity when the molar ratios of SGS/DTAB and SGS/CTAB mixtures are 9:10. The formation of catanionic complexes shields the electrostatic repulsion between surfactant molecules and lowers the electrostatic adsorption barrier. Therefore, SGS/DTAB and SGS/CTAB mixtures exhibit higher adsorption rates than either component alone. The effects of oscillating frequency and surfactant concentration on the surface dilational properties of SGS, DTAB, CTAB, SGS/DTAB, and SGS/CTAB mixtures were also determined. As the oscillating frequency increases, the dilational elasticity of these surfactants gradually increases. The dilational elasticity peaks at a certain concentration, which is less than the critical micelle concentration (CMC). Results show that the dilational elasticity of SGS/DTAB and SGS/CTAB mixtures is higher than that of either component, resulting from the formation of a denser monomolecular adsorption layer at the air–water interface. Our study provides a basis for understanding the interaction mechanism of catanionic surfactant mixtures containing Gemini surfactant at the air–water interface.     

The study of Sunset Yellow anionic dye interaction with gemini and conventional cationic surfactants in aqueous solution

In the present study, the interaction of an anionic azo dye, Sunset Yellow, with two cationic gemini surfactants with different spacer lengths (s = 3, 6 methylene groups) and their monomeric counterpart, dodecyl trimethyl ammonium bromide (DTAB), was investigated by surface tension, UV–Vis spectroscopy, and zeta potential measurements. The critical micelle concentration (CMC) was determined from plots of the surface tension (γ) as a function of the logarithm of total surfactant concentration. Moreover, the values of binding constants (K_b) of dye-surfactant complexes were calculated by UV–Vis spectroscopy. The UV–Vis spectra showed that the dye–surfactant interaction occurred in the solution at concentrations far below the CMC of each surfactant. The gemini surfactant with a shorter spacer showed stronger interaction with dye in comparison to DTAB and the gemini with longer spacer. The effect of surfactant chemical structure on solubilization of dye-surfactant aggregates at surfactant concentration above CMC was investigated by zeta potential.     

Suspensions of Iron Oxide Nanoparticles Stabilized by Anionic Surfactants

Two common anionic surfactants, sodium oleate (SO) and sodium dodecyl benzene sulfonate (SDBS) were used to re‐suspend iron oxide nanoparticles in aqueous solutions. At certain SO concentrations, the SO formulations produced highly stable suspensions. In contrast, SDBS‐stabilized nanoparticles exhibited poor stability at all concentrations. The adsorption isotherm of SO on iron oxide nanoparticles revealed that stable suspensions were obtained when the equilibrium SO concentration (after adsorption) reached its critical micelle concentration (CMC). At this “optimal” condition, the maximum SO adsorption was reached, and the zeta‐potential of the particles was highly negative (～ ?50 mV). According to the SO isotherm, this optimal formulation coincided with the formation of a highly compact SO bilayer. The SDBS isotherm, on the other hand, revealed that SDBS is not strongly adsorbed on the surface of iron oxide nanoparticles and that is likely that a patchy, loosely packed bilayer, is formed on the surface of the iron oxide nanoparticles when the equilibrium SDBS concentration reaches its CMC. The DLVO theory confirmed the connection between formulation conditions and the corresponding stability. This works confirmed that the formation of a surfactant bilayer is an important element in producing stable nanoparticle suspensions with anionic surfactants. It was also confirmed that for anionic surfactants, electrostatic repulsions are an important factor in establishing an energy barrier against flocculation. This work also introduced two more elements into the design of nanoparticle suspensions. The first element is that, in order to ensure the best possible dispersion, the surfactant concentration in solution at equilibrium with the adsorbed surfactant should be close or slightly above its CMC. The second element is that the molecular structure of the surfactant should facilitate the formation of closely packed bilayers.     

Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants

In this study, the gemini surfactants of the alkanediyl-α-ω-bis(alkyl dimethyl ammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as “m-2-m” (m = 10, 12 and 16) and, on the other hand, with n-C₁₆ alkyl groups and different spacers containing s carbon atoms, referred to as “16-s-16” (s = 2, 6, 10 and Ar (8)) have been synthesized, purified and characterized. The critical micelle concentration (CMC), micelle ionization degree (α) and Gibbs free energy of micellization (∆G _mic) of these surfactants and the monomeric cationic surfactants DTAB and CTAB have been determined by means of electric conductivity measurements. In addition, the temperature dependence of the CMC was determined for the 10-2-10 gemini surfactant. The CMCs of the gemini surfactants are found to be much lower than those of the corresponding monomeric surfactants and the effect of the hydrophobic alkyl chain length is more important than that of the spacer. The CMC of 16-s-16 passes through a maximum of (or around) s = 6 and then decreases for s = 10. The presence of a maximum CMC is explained by the contribution of a change of conformation of the surfactant with increasing spacer chain length. The changes of α with s and m are found qualitatively similar to those found for CMC values. The values of ∆G _mic are more negative for the dimers than for the monomers and also change with an increasing spacer carbon number, as CMC values do. The thermodynamic parameters of micellization indicate that the micellization of 10-2-10 is enthalpy driven.     

Styrene Solubilization and Adsolubilization on an Aluminum Oxide Surface Using Linker Molecules and Extended Surfactants

The impact of lipophilic linker and extended surfactant properties on admicelle formation and styrene adsolubilization were evaluated through adsorption and adsolubilization studies on aluminum oxide. While linker-based systems achieved a higher maximum adsorption than extended surfactants, the extended surfactants reached maximum adsorption at a lower aqueous surfactant concentration. Results of solubilization and adsolubilization studies are summarized by the extent of solute solubilization into micelles and admicelles, as captured through the micellar partition coefficient, K _mic, and the admicellar partition coefficient, K _adm. The extended-surfactant-based micelles showed greater solubilization capacity than linker-based micelles. Relative to the effect of the number of propoxy groups for extended surfactants with the same alkyl chain length, the results show that the solubilization capacity increases when the PO number increases for both C12,13- and C14,15-based surfactant series. Thus, adsolubilization using extended-surfactant-based admicelles showed adsolubilization enhancement but required lower amounts of surfactants to form admicelles. These results thus provide insights into external and internal linker-based and extended-surfactant-based admicellar systems and highlight the differences observed between them and admicelles based on conventional surfactant systems.

Study of the Influence of Gemini Cationic Surfactants on the Dyeing and Fastness Properties of Polyester Fabrics Using Naphthalimide Dyes

In this paper, the dyeing and fastness properties of three monoazo naphthalimide dyes including different imide groups (dye 1: ethyl amine, dye 2: ethyl glycinate and dye 3: glycine) on a polyester fabric were investigated in the presence of two gemini cationic surfactants (symbolized as 12‐4‐12 or 14‐4‐14) and a conventional single chain surfactant, dodecyltrimethylammonium bromide (DTAB). The color strength (K/S) of naphthalimide dyes on polyester fabric was measured through the reflectance spectrophotometric method, and the values obtained in the presence of different cationic surfactants increased in the order of dye 3 < dye 2 < dye 1. Although the K/S values indicated that the gemini cationic surfactants had almost no effect on the dyeing behavior of dye 1, but they were effective in dyeing ability of dye 2 and dye 3. The data for dye 2 demonstrated that build up of polyester fabrics in the presence of gemini surfactants are more than the conventional cationic surfactant, and also K/S values of dye 3 on polyester fabrics were in the order: DTAB > 12‐4‐12 > 14‐4‐14. It was found that the washing and rubbing fastness properties improved with increasing the concentration of surfactants. In addition, the sublimation fastness of dye 3 was more than the other dyes owing to the presence of a polar group in its chemical structure, and the light fastness of naphthalimide dyes on polyester fabrics was generally moderate.     

DODAC对水热法插层改性蒙脱土结构和性能的影响

选用阳离子表面活性剂双十八烷基二甲基氯化铵(DODAC)作为改性剂,通过水热法插层改性钠基蒙脱土(Na-MMT).采用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TGA)、扫描电镜(SEM)等手段研究了水热插层法和DODAC添加量对有机化蒙脱土结构和性能的影响.研究结果表明:水热法的插层改性效果优于常规插层改性方法,DODAC添加量对有机化蒙脱土的层间结构影响显著,随改性剂添加量增加,有机化蒙脱土的层间距变大,DODAC分子的层间堆叠方式依次由单层、双层向伪三层、类石蜡复合型结构转变.当DODAC添加量为2.0CEC时,水热插层改性效果最为明显.     

烷基苯磺酸盐Gemini表面活性剂的结构与界面性质

以烷基酰氯为原料,经傅克酰基化反应、格林反应、催化氢化还原及磺化、中和等步骤,合成了10-4-10、12-4-12和10-6-10(10和12代表疏水基碳数,4和6代表连接基团碳数)3种不同结构的双烷基双苯双磺酸盐Gemini表面活性剂,并用核磁共振氢谱和电喷雾质谱对产物进行了结构鉴定。用旋滴法测定了其水溶液与正庚烷的界面张力,发现磺酸盐Gemini表面活性剂的CMC比对应的传统的表面活性剂的CMC低两个数量级,并且随着疏水基碳数或连接基团碳数的增加而降低。10-4-10、12-4-12和10-6-10的饱和吸附面积(Amin)分别为0.23、0.35和0.97 nm2,饱和吸附量(Γmax)分别为7.37×10-10、4.65×10-10和1.72×10-10mol/cm2,临界胶束浓度下的界面张力(γCMC)分别为3.60、3.06和1.89 mN/m。     

Comparison of a Cationic Gemini Surfactant and the Corresponding Monomeric Surfactant for Corrosion Protection of Mild Steel in Hydrochloric Acid

A cationic gemini surfactant, N,N′-didodecyl-N,N,N′,N′-tetramethyl-1,4-butanediammonium dibromide (12-4-12) and the corresponding monomeric surfactant dodecyltrimethylammonium bromide were compared with respect to corrosion inhibition efficiency in 1 M hydrochloric acid solution. Polarization and electrochemical impedance spectroscopy were used to evaluate corrosion inhibition. The 12-4-12 surfactant showed an extremely high corrosion inhibition efficiency at very low concentration. Surface tension measurements performed under the strongly acidic conditions revealed that the gemini surfactant is remarkably electrolyte tolerant, which is beneficial for adsorption at the steel surface.     

双子阳离子表面活性剂改性蒙脱土的制备与表征

合成了新型双子阳离子表面活性剂Gemini-16,并用其对钠基蒙脱土进行改性。红外光谱(FTIR)、热重(TGA)分析表明,Gemini-16已插层到蒙脱土片层间。X射线衍射(XRD)表明,改性后蒙脱土层间距从1.47 nm增加到3.48 nm。分散性实验表明,经Gemini-16改性的蒙脱土在液体石蜡中表现出很好的相容性和分散性,改性效果优于目前常用的CTAB处理效果,更有利于聚合物单体进入蒙脱土层间形成聚合物/蒙脱土纳米复合材料。     

Changes in the morphology of organoclays with HDTMA surfactant loading

The detailed understanding of the interlayer structure of organoclays is of importance in the design of organoclay based materials and their industrial applications. In this study, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to provide new insights into the interlayer structure and morphology of HDTMA⁺/montmorillonite organoclays. XRD patterns show that thermal treatment has an important effect on the stability of organoclays, reflected by significant changes in the basal spacing. TEM and SEM micrographs demonstrate that the organoclays with lower surfactant packing density are mainly composed of irregular layer stacking with a number of curved organoclay layers, while those with higher surfactant packing density are mainly composed of regularly intercalated and flat layers. Variations of the interlayer distances exist in all organoclays and are more pronounced in the organoclays with lower surfactant packing density. This study demonstrates that not only the arrangement model of surfactant but also the morphology of organoclay strongly depend on the surfactant packing density within the montmorillonite interlayer space.     

阳离子型双子表面活性剂的合成及表面活性

合成了一种季铵盐型双子表面活性剂Gem in i 12-3-12,采用红外光谱、元素分析和两相滴定法对其结构和纯度进行了分析,测定了不同浓度表面活性剂水溶液的表面张力,并得到临界胶束浓度(CMC)、饱和吸附量(Γm ax)、单分子饱和吸附面积(Am in)。结果表明,Gem in i 12-3-12的收率为77.2%,纯度为98.4%,它与相应的单尾基十二烷基三甲基溴化铵(DTAB)的表面活性相当,但CMC比DTAB低14倍左右。