Florent Jasinski  Thiago R. Guimares  Samantha David  Caroline Suniary  Toby Funston  Yutaka Takahashi  Yukishige Kondo  Per B. Zetterlund 《Macromolecular rapid communications》2019,40(22)

Production of aqueous dispersions of polymeric nanoparticles via heterogeneous radical polymerization in emulsion‐type systems is of enormous commercial importance. The ability to reversibly destabilize such a latex is highly desirable, for example, to save transportation costs. Herein, a method for synthesis of photo‐responsive polymer latexes that can be destabilized (leading to sedimentation) by only using UV irradiation (no addition of chemicals or change in the experimental conditions) and subsequently redispersed by stirring under visible light irradiation is described. The destabilization/redispersion mechanism relies on photoinduced trans‐cis isomerization of the cationic diazene surfactant 2‐(4‐(4‐butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (C4AzoTAB) used in conjunction with the anionic surfactant sodium dodecyl sulfate. It is demonstrated that reversible destabilization can be achieved very rapidly (90 s residence time) employing continuous flow technology.  相似文献   

    

Andrey Yu. Vlasov  Anastasia V. Venediktova  Pavel V. Ivanov  Alexandra L. Nikolaeva  Yuri A. Anufrikov  Vladimir Yu. Venediktov 《physica status solidi b》2019,256(12)

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《Comptes Rendus Chimie》2019,22(5):355-362

In this study, the effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid (HCl) solution was investigated by using dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TTAC), cetyl trimethyl ammonium chloride (CTAC), and octadecyl trimethyl ammonium chloride (OTAC) as corrosion inhibitors to uncover their structure–efficiency relationships. The effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in HCl solution was studied under different conditions, such as corrosion inhibitor concentration, temperature, and acidity, and this was done using the weightlessness method. The results obtained show that these inhibitors have high corrosion inhibition effect on A₃ steel, and the corrosion inhibition efficiency is dependent on the length of the alkyl chain. At the same concentration, the longer the alkyl chain, the weaker the corrosion inhibition effect. When the temperature was 50 °C and the concentration of corrosion inhibitor was 70 mg/L, the corrosion inhibition efficiency order of the four cationic surfactants was DTAC > TTAC > CTAC > OTAC. Besides, the experimental results obtained show that the adsorption of the inhibitor on the A₃ steel surface conforms to the Langmuir type isotherm, and then the corresponding adsorption thermodynamic parameters were obtained according to these parameters. It was observed that ΔH, ΔS, and E_a increased with increase in the length of the alkyl chain. The adsorption of the inhibitor on the steel surface is an exothermic, spontaneous, entropy process.  相似文献   

    

Dr. Da Li  Prof. Wei Zhao  Lei Cao  Prof. Yiying Gao  Prof. Yahui Liu  Prof. Weijing Wang  Prof. Tao Qi 《ChemSusChem》2019,12(19):4412-4420

A mixed-surfactant-assisted method was developed to synthesize dual-phase Li₄Ti₅O₁₂-TiO₂ hierarchical microspheres. The ratio of anionic/cationic surfactant could regulate the primary structure morphology and the dual-phase ratio of the final product, in which the primary structure morphology could be stacked nanosheets, small nanoparticles, or large nanoparticles. The sample with a primary structure morphology of small nanoparticles had the highest specific surface area of 79.38 m² g⁻¹ and the best electrochemical performance because of its high Li⁺ migration rate, low polarization, and appropriate TiO₂ content. Its capacity reached 153.5 mA h g⁻¹ at a current rate of 40 C, and it retained nearly 100 % of its capacity after 100 cycles. A self-assembly mechanism of the mixed surfactant was highlighted to explain the formation of hierarchical microspheres. The physical and electrochemical properties of obtained material were correlated effectively.  相似文献   

    

《Journal of Chemometrics》2018,32(8)

Surfactant‐based enhanced oil recovery techniques are known as promising methods for mobilizing the trapped oil in porous media. Surfactants can improve oil recovery by modifying the wettability of rock minerals and also by reducing the interfacial tension between injected water and the trapped oil. Natural surfactants have been introduced as good candidates for enhanced oil recovery applications. In addition, they are less expensive and also have less detrimental environmental effects in comparison with the industrial surfactants. Various empirical models have been proposed for simulating the kinetic behavior of surfactants adsorption, but these models suffer from overestimation and underestimation and they cannot be generalized for even a type of surfactant. Therefore, it is crucial to develop a new model that can overcome these issues. In this study, a new simple, rapid, and accurate model based on least square support vector machines (LSSVMs) was developed for predicting the kinetic adsorption density of natural surfactants on both sandstone and carbonate minerals. Coupled simulated annealing algorithm (CSA) is used for tuning the parameters of the model. Predicted values by this model were in an excellent agreement with experimental values with a coefficient of determination of 0.990. The results demonstrated that the proposed LSSVM‐CSA model has the best performance in comparison with the other well‐established kinetic models. Furthermore, the model reliability was investigated over input parameters changes and showed the acceptable efficiency of the proposed model.  相似文献   

    

Anwar Ali  Mujeeb Alam  Ummer Farooq  Sahar Uzair 《Physics and Chemistry of Liquids》2018,56(4):528-543

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Dr. Jie Wang  Yunling Xu  Dr. Bing Ding  Zhi Chang  Prof. Xiaogang Zhang  Prof. Yusuke Yamauchi  Prof. Kevin C.‐W. Wu 《Angewandte Chemie (International ed. in English)》2018,57(11):2729-2729

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Isabell Hofmann  Melanie König  Dr. Carlos G. Lopez  Dr. Ljubica Vojcic  Prof. Dr. Walter Richtering  Prof. Dr. Ulrich Schwaneberg  Dr. Larisa A. Tsarkova 《Angewandte Chemie (International ed. in English)》2018,57(30):9402-9407

Reported is an unanticipated mechanism of attractive electrostatic interactions of fully neutralized polyacrylic acid (PAA) with like‐charged surfactants. Amphiphilic polymer‐surfactant complexes with high interfacial activity and a solubilization capacity exceeding that of conventional micelles are formed by bridging with Ca²⁺ ions. Incorporation of a protease into such dynamic nanoreactors results in a synergistically enhanced cleaning performance because of the improved solubilization of poorly water‐soluble immobilized proteins. Competitive interfacial and intermolecular interactions on different time‐ and length‐scales have been resolved using colorimetric analysis, dynamic tensiometry, light scattering, and molecular dynamic simulations. The discovered bridging association mechanism suggests reengineering of surfactant/polymer/enzyme formulations of modern detergents and opens new opportunities in advancing labile delivery systems.  相似文献   

    

《Journal of separation science》2018,41(2):475-482

Surfactant‐assisted electromembrane extraction coupled with cyclodextrin‐modified capillary electrophoresis was developed for the separation and determination of Tranylcypromine enantiomers in biological samples. This combination would provide a new strategy for selective and sensitive determination of target analytes. The addition of surfactant in the donor solution improved the analyte transport into the lumen of hollow fiber that resulted in an enhancement in the analytes migration into acceptor solution. Optimization of the variables, affecting proposed method, was carried out and best results were achieved with a 175 V potential as driving force of the electromembrane extraction, 2‐nitrophenyloctylether as the supported liquid membrane, donor solution containing 0.2 mM Triton X‐100 with pH 3 and 0.1 M HCl for acceptor solution. Then, the extract was analyzed using cyclodextrin‐modified capillary electrophoresis method for separation of Tranylcypromine enantiomers. The best results were obtained with a phosphate running buffer (100 mM, pH 2.0) containing 7% w/v hydroxypropyl‐α‐cyclodextrin. Under the optimum conditions, a low limit of detection (3.03 ng/mL), good linearity (R² > 0.9953), and relative standard deviations below 4.0% (n = 5) were obtained. Finally, this procedure was applied to determine the concentration of Tranylcypromine enantiomers in urine samples with satisfactory results.  相似文献   

    

《Angewandte Chemie (International ed. in English)》2017,56(20):5475-5479

Gaining external control over self‐organization is of vital importance for future smart materials. Surfactants are extremely valuable for the synthesis of diverse nanomaterials. Their self‐assembly is dictated by microphase separation, the hydrophobic effect, and head‐group repulsion. It is desirable to supplement surfactants with an added mode of long‐range and directional interaction. Magnetic forces are ideal, as they are not shielded in water. We report on surfactants with heads containing tightly bound transition‐metal centers. The magnetic moment of the head was varied systematically while keeping shape and charge constant. Changes in the magnetic moment of the head led to notable differences in surface tension, aggregate size, and contact angle, which could also be altered by an external magnetic field. The most astonishing result was that the use of magnetic surfactants as structure‐directing agents enabled the formation of porous solids with 12‐fold rotational symmetry.  相似文献