Effects of Nonionic, Cationic, and Mixed Nonionic-Cationic Surfactants on the Acid-Base Behavior of Phenyl Salicylate

The effects of Brij 35 micelles, CTABr micelles, and mixed Brij 35–CTABr micelles on the acid–base behavior of phenyl salicylate (PST) have been studied in aqueous solution containing 2% v/v acetonitrile. The apparent pK_b (pK^app_b) of PST is decreased by 1.5 pK units with the increase in [Brij 35] from 0 to 0.02 M which is attributed to micellar medium effect. The values of pK^app_b remain almost independent of [CTABr] within its range 0.01–0.03 M. The increase in [CTABr] from 0 to 0.03 M in aqueous solution containing 0.02 M Brij 35 has not resulted in a change in pK^app_b. This shows that the characeristic structural features of nonionic Brij 35 micelles remain essentially unchanged on addition of CTABr under the present experimental conditions.     

Effects of Various Schiff Base Ligands and Micelles on the Hydrolytic Kinetics of p-Nitrophenyl Picolinate

In this article, the effects of different micelles and Schiff base ligands on the hydrolytic kinetics of p-nitrophenyl picolinate (PNPP) were evaluated. The results reveal that the biggest rate enhancement for PNPP hydrolysis was given in Gemini 16-6-16 micellar solution relative to other four reaction media, that is, cetyltrimethylammonium bromide (CTAB), n-lauroylsarcosine sodium (LSS), polyoxyethylene (23) lauryl ether (Brij35) and pure buffer. Moreover, the hydrolytic rates of PNPP in other four media decreased in the order LSS > CTAB > Buffer > Brij35. The structural effects of Mn(III) catalysts clearly testify that a relatively open active site facilitates the formation of reactive substrate-catalyst complex.     

Role of the Surfactant Structure in the Behavior of Hydrophobic Ionic Liquids within Aqueous Micellar Solutions

The behavior of an ionic liquid (IL) within aqueous micellar solutions is governed by its unique property to act as both an electrolyte and a cosolvent. The influence of the surfactant structure on the properties of aqueous micellar solutions of zwitterionic SB‐12, nonionic Brij‐35 and TX‐100, and anionic sodium dodecyl sulfate (SDS) in the presence of the “hydrophobic” IL 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim][PF₆]) is assessed along with the possibility of forming oil‐in‐water microemulsions in which the IL acts as the “oil” phase. The solubility of [bmim][PF₆] within aqueous micellar solutions increases with increasing surfactant concentration. In contrast to anionic SDS, the zwitterionic and nonionic surfactant solutions solubilize more [bmim][PF₆] at higher concentrations and the average aggregate size remains almost unchanged. The formation of IL‐in‐water microemulsions when the concentration of [bmim][PF₆] is above its aqueous solubility is suggested for nonionic Brij‐35 and TX‐100 aqueous surfactant solutions.     

Kinetics of metal ion complex formation in micellar media. A comparison between normal and polymerized micelles

Micellar media can be used to investigate the rate of complex formation between hydrophobic extractants and metal ions. Acceleration or retardation effects may be obtained, depending on factors such as the nature of the surfactant, the hydrophilic/lipophilic character and ionization state of the extractant, etc. The present work was aimed at studying the influence of some specific parameters in producing retardation effects, which have potential application for performing separation of metal ions on a kinetic basis. The stopped-flow technique was used to measure the rate of complex formation between Cu²⁺ and complexing agents with varying alkyl chain length. Micelles made of the nonionic surfactants C₁₂EO₆, Triton X-100 and Brij 35 were first considered, which did not show any direct correlation between the rate of complex formation and the thickness of the hydrophilic layer constituted by the polar heads of the surfactant molecules.In a second approach, we have used polymerized micelles obtained from undec-10-enyltrimethyl ammonium bromide, which we assumed to be more rigid than normal micelles. Although the absence of CMC was confirmed, the rates measured in these polymerized micelles were larger than those obtained in micellar solutions of CTAB and DTAB. The results are discussed in relation with the nature of the hydrophobic domains in the different situations.Institut Nancéien de Chimie Moléculaire (I.N.C.M.), FU CNRS n=8     

Adsorption properties of phenolic resin-based mesoporous carbons obtained by using mixed templates of Pluronic F127 and Brij 58 or Brij 78 polymers

Phenolic resin-based mesoporous carbons were synthesized by using mixed templates of Pluronic F127 and Brij 58 or Brij 78. For the purpose of comparison three samples of nanoporous carbons were prepared by using single templates of Pluronic F127, Brij 58 and Brij 78 polymers, respectively. Adsorption properties of the aforementioned carbons were studied by nitrogen adsorption at ?196?°C. The resulting carbons featured high specific surface areas ranging from 641 m²/g for the sample obtained in the presence of Brij 58 polymer to 825 m²/g for the carbon prepared by using a mixed template containing 23% of Pluronic F127 and 77% of Brij 58 and from 588 m²/g for the sample obtained in the presence of Brij 78 polymer to 813 m²/g for the carbon prepared by using Pluronic F127 only. It was shown that the width of mesopores increases with increasing amount of Brij 58 or Brij 78 in the mixture of one of these polymers with Pluronic F127, suggesting that Brij polymers act also as micelle expanders.     

Brij类表面活性剂与Laponite纳米颗粒的相互作用及其稳定乳液的研究

通过表面张力、Zeta电位和流变学参数的测定, 研究了聚氧乙烯烷基醚类非离子型表面活性剂(Brij 30和Brij 35)在合成锂皂石(Laponite)纳米颗粒表面的吸附及对Laponite水分散体系中颗粒间相互作用和体系粘度的影响. 结果表明, 这类表面活性剂能显著地吸附在Laponite颗粒表面上, 且吸附量随其分子中POE链长短而不同. 这种吸附没有改变Laponite粒子的带电性质, 但一定程度地降低了Laponite颗粒Zeta电位; 吸附也会减弱颗粒间的相互作用, 降低体系的粘度. 实验以Laponite和Brij为乳化剂, 制备了O/W型乳状液. 乳液稳定性变化和乳液粒径分布结果表明, 体系中Brij的浓度较低时, 乳液的性质主要是由Laponite颗粒决定的; 而Brij浓度较高时, 则主要取决于Brij表面活性剂. 高速剪切含Brij的Laponite水分散体系, 剪切后表面张力随时间的变化表明, 剪切作用会使得吸附在Laponite颗粒表面的Brij分子不同程度地解吸下来. 这也意味着乳液制备时, 高速剪切作用也会造成Brij分子自Laponite颗粒表面的脱附, 这可能是非离子表面活性剂与阳离子表面活性剂对负电固体颗粒稳定乳液影响不同的原因.     

Adsorption of Brij 35-dodecylpyridinium bromide mixtures at air-aqueous solution and Teflon-aqueous solution interfaces

Tensiometry, spectrophotometry, the radioactive-tracer technique, and contact angle measurements are employed to study the adsorption of mixtures of a nonionic surfactant Brij 35 and a cationic surfactant dodecylpyridinium bromide (DDPB) at interfaces between their solutions and air or Teflon. It is established that adsorption layers at both of the interfaces are enriched with Brij 35. Brij 35 adsorption on Teflon is nearly independent of the presence of DDPB. On the contrary, DDPB adsorption is enhanced in the presence of Brij 35. Negative deviations from the ideal behavior are revealed for mixtures with small fractions of Brij 35 with respect to a decrease in the interfacial tension in air-solution and Teflon-solution systems.     

Mixed micellar liquid chromatography methods: modelling quantitative retention-activity relationships of angiotensin converting enzyme inhibitors

The capability of biopartitioning micellar chromatography (BMC), using pure Brij35 solution and mixed micellar system of Brij35-SDS (85:15) as mobile phase, to describe and estimate bioactivities of angiotensin converting enzyme inhibitors at different pH has been studied. Quantitative retention-activity relationships (QRAR) in BMC were investigated for these compounds. The obtained BMC(Brij35-SDS)-QRAR models were compared with the traditional BMC(Brij35)-QRAR, and better statistically models were obtained using Brij35-SDS retention data. The superiority of BMC(Brij35-SDS)-QRAR is due to the fact that the mixed micellar mobile phase can simulate the resting membrane potential and the conformation of the long hydrophilic polyoxyethylene chains remains unchanged.     

苄泽类非离子型表面活性剂与明胶的相互作用

采用表面张力和稳态荧光光谱法考察了具有不同疏水结构的2种苄泽类非离子型表面活性剂Brij58和Brij78与明胶之间的相互作用。结果表明,苄泽类非离子型表面活性剂与明胶之间相互作用的驱动力为疏水作用力,且两者之间的相互作用受到其疏水基团的影响,Brij78在明胶溶液中的临界聚集浓度低于Brij58体系,表明疏水链更长的Brij78与明胶之间的相互作用更强。明胶分子的内源荧光光谱强度受苄泽类非离子型表面活性剂的影响,但最大吸收峰位置未发生蓝移,Brij78/明胶体系的内源荧光强度高于Brij58/明胶体系;此外,表面活性剂浓度较低时,明胶的加入使溶液中疏水微区极性明显降低,且明胶浓度越大降低程度越大。     

Microstructure and rheological properties of liquid crystallines formed in Brij 97/water/IPM system

The phase diagram of Brij 97/water/IPM systems was determined at 25 degrees C. Rich liquid crystalline phases including Lalpha, H1, and cubic Fd3m phases were identified by means of small angle X-ray scattering (SAXS). Microstructure transitions of liquid crystals with changes in surfactant concentration and oil content are explained qualitatively by the surfactant packing parameter (vL/aSlc). Dynamic rheological results indicate that all three kinds of liquid crystals investigated show high elasticity. The lamellar, Lalpha, phases formed in Brij 97/water with two different oils, oleic acid and geraniol, were also studied in comparison with those of Brij 97/water/IPM systems. The strength of the network of lamellar phases formed in Brij 97/water/oleic acid and Brij 97/water/geraniol systems are appreciably stronger than for Brij 97/water/IPM systems, indicated by the smaller area of surfactant molecules at the interface and the higher moduli (G' and G').     

Pseudo-homogeneous micelle extraction of ion-associates formed between tetrabutylammonium ion and some aromatic sulfonate ions into nonionic surfactant micelle studied through the mobility measurements in capillary zone electrophoresis

Ion-association extraction of some aromatic sulfonate ions including alkylbenzene sulfonates with tetrabutylammonium ion (TBA+) into nonionic surfactant micelle has been investigated through the changes in the electrophoretic mobility. Nonionic surfactants of Brij 35 and Brij 58 were used as micelle substrates to which the ion-associates formed could distribute. The electrophoretic mobility of the aromatic sulfonate ions was measured by capillary zone electrophoresis in the presence of TBA+ and/or the nonionic surfactant to determine ion-association constants (K(ass)), binding constants of the anions to the nonionic surfactant micelle (K(B)), and binding constants of the ion-associates to the nonionic surfactant micelle (K(B,IA)). Nonlinear phenomena induced with the alkyl chain moiety were observed on K(ass) and K(B) by its linear structure and the mixed micelle formation, respectively. Larger K(B) values were obtained with Brij 58 as micelle matrix than with Brij 35, while the differences in K(B,IA) were small between Brij 58 and Brij 35.     

非离子表面活性剂Brij 30诱导离子液体型表面活性剂C16imC8Br蠕虫状胶束向凝胶的转变

Wormlike micelles and low-molecular-weight hydrogels are composed of three-dimensional networks that endow them with viscoelasticity, but their viscoelastic properties are markedly different. The viscosity of wormlike micelles is attributed to a transient network, while that of gels is due to a stable network. Under certain conditions, wormlike micelles can undergo transition to gels with an increase in the density of the network. In our previous study, we found that the wormlike micelle formed by the ionic liquid-type surfactant 1-hexadecyl-3-octyl imidazolium bromide ([C₁₆imC₈]Br) without any additive has high viscoelasticity. The inclusion of a nonionic surfactant polyoxyethylene lauryl ether (Brij 30) is expected to enhance the viscoelasticity of [C₁₆imC₈]Br wormlike micelles via electrostatic shielding and strong hydrophobic interactions, which may be the driving factor for the wormlike micelle-to-gel structural transition. The morphology and viscoelasticity of [C₁₆imC₈]Br wormlike micelles with Brij 30 were studied as a function of concentration by rheological measurements and freeze-fracture transmission electron microscopy. The thermal stability and gel-sol transition temperature of the Brij 30/[C₁₆imC₈]Br gels were studied using rheology. The interaction between Brij 30 and [C₁₆imC₈]Br was studied by zeta potential measurements and nuclear magnetic resonance (NMR) spectroscopy. Upon the inclusion of Brij 30 into the [C₁₆imC₈]Br wormlike micelles, the viscoelasticity of the Brij 30/[C₁₆imC₈]Br samples first increased and then decreased with an increase in the Brij 30 concentration, at different initial concentrations of [C₁₆imC₈]Br. At a certain Brij 30 concentration, the Brij 30/[C₁₆imC₈]Br samples rheologically behaved as a gel. The maximum viscoelasticity of the [C₁₆imC₈]Br (4.06% (w))/Brij 30 gel was observed at a Brij 30/[C₁₆imC₈]Br molar ratio of 4.55. The viscoelasticity of the Brij 30/[C₁₆imC₈]Br gels was positively correlated with the activation energy of the gels. The gel-sol transition temperature of the Brij 30/[C₁₆imC₈]Br gels also increased first and then decreased with an increase in the Brij 30 concentration. The highest gel-sol transition temperature of the Brij 30/[C₁₆imC₈]Br (4.06% (w)) gel was observed at a Brij 30/[C₁₆imC₈]Br molar ratio of 2.93. The Brij 30 concentration had a notable impact on the viscoelasticity, thermal stability, and gel-sol transition temperature of the Brij 30/[C₁₆imC₈]Br gels. The zeta potential and ¹H NMR measurements revealed that the neutral Brij 30 molecules are inserted into the palisade layer of the [C₁₆imC₈]Br wormlike micelles via hydrophobic interactions. This decreased the electrostatic repulsion between the [C₁₆imC₈]Br headgroups, which in turn induced the rapid growth of wormlike micelles and the formation of a stiffer network structure. Finally, the wormlike micelles underwent a structural transition to gels. The obtained results would aid in better understanding the relationship between wormlike micelles and gels, and may be of potential value for industrial and technological applications.     

THE EFFECT OF SURFACTANT MICELLES ON THE ALKALINE HYDROLYSIS OF DIMETHYLFORMAMIDE

The alkaline hydrolysis of dimethylformamide has been studied at 40'C in micellar solutions of single surfactant (CTAB. SDS. Brij 35) with the analog thermoanalytical curve method of thermokinetics. A kinetic equation of micellar catalysis under the condition of highter reactant concentration than micellar concentration ([S]>[M]) has been derived from the pseudophase model of micellar catalysis and some relative assumptions, The kinetic parameters. k_m, k_2mand the association constant of reactant with micelle K₁, have been calculated in this way. the results indicate that these surfactant micelles exhibit catalytic effect on the reaction. This is attributed to the micropolarity and local concentration effect of micelles.     

Self aggregation of binary mixtures of sodium dodecyl sulfate and polyoxyethylene alkyl ethers in aqueous solution

The mixed micelles of sodium dodecyl sulphate (SDS) with Brij35 and Brij 97 were studied separately by fluorescence measurement using pyrene as fluorescent probe. In the range of 0–1.0 mole fraction (X) of added SDS to Brij solutions, the cmc value of the mixed micelles varies from 0.085 to 8 mmol with Brij 35 and 0.04 to 8 mmol with Brij 97. The aggregation number also changes. A measure of the stability of mixed micelles is also presented. The interaction parameter ₁₂ and the chain–chain contribution parameter (B₁) are extracted from the analysis of the results. This parameter B₁ is related to the standard free energy change associated with the introduction of one ionic species into a nonionic micelle coupled with the release of one nonionic species from the micelle. The clouding behaviour of Brij 97 in the presence of SDS was investigated and the associated thermodynamic parameters of clouding were generated and discussed.     

纳米复合模板水凝胶的制备及其性能

以非离子表面活性剂聚氧乙烯(20)鲸蜡醇醚(Brij58)为模板, 采用自由基聚合制备得到聚(N-异丙基丙烯酰胺)/Brij58/粘土纳米复合模板水凝胶(PLH). 相比于传统纳米复合水凝胶, PLH水凝胶力学性能与亲水性明显改善. 场发射扫描电镜(FESEM)结果表明: Brij58的引入导致传统纳米复合水凝胶的孔洞数量增加, 孔与孔相互贯穿, 大孔结构更加规整, 大孔之间由众多小孔连接. 拉伸应力-应变、储能模量和溶胀动力学研究结果表明, 断裂应力、断裂负载和断裂伸长率随Brij58含量的增加呈先增加后降低的趋势, 然而水凝胶储能模量与最大溶胀度随Brij58含量的增加而增加. 同时, 表面接触角结果表明: 由于Brij58的模板作用和Brij58同粘土之间的吸附作用, 使PLH水凝胶表面接触角先增大后减小.     

用胶束液相色谱模拟生物膜预测药物的醇-水分配系数log P

通过比较药物在不同类型表面活性剂的胶束液相色谱中的容量因子与药物的醇-水分配系数(log P)的相关性, 发现药物在非离子型表面活性剂Brij35作为流动相的胶束液相色谱中的容量因子与其文献中报道的log P间有一定的相关性, 进一步考察了Brij35浓度对药物保留的影响, 并建立了药物在不同浓度的Brij35胶束液相色谱中的容量因子与文献中log P的相关关系, 该方法简单、快速, 将为药物的疏水性评价提供重要的参考价值.     

ENERGY TRANSFER IN TRITON X-405 MICELLES: THE EFFECTS OF TEMPERATURE AND BRIJ 35

–Energy transfer from the phenyl groups of micellar Triton X-405 (TX-405) to solubilized pyrene molecules has been measured at a range of temperatures and in the presence of different polyoxyethylene 23 lauryl ether (Brij 35) concentrations. Increases in temperature lead to elimination of water from the outer, wet, micelle layer and an inward movement of associated pyrene. The addition of Brij also leads to a reduction in polarity of the microenvironment of pyrene. However, sensitization is observed even at high Brij concentrations. The donor/acceptor separation caused by the introduction of Brij proceeds slowly, continuing for several minutes after its addition to micellar TX-405.     

Polysulfone/Brij‐58 blend nanofiltration membranes: preparation,morphology and performance

In present research, novel asymmetric polysulfone (PSF) membranes with high hydrophilicity and noticeable rejection of arsenic, as one of the major environmental problems, were prepared from PSF/Brij‐58/NMP (1‐methyl‐2‐pyrrolidone) system via immersion precipitation. Pure water was used as gelation media. The variation effect of coagulation bath temperature (CBT) and addition of Brij‐58 on morphology, wettabiliy, pure water permeation flux and rejection of As (III) and As (V), as two dominant states of arsenic in the nature, were studied by scanning electron microscopy, contact angle measuring instrument and experimental setup. The results demonstrated that both hydrophilicity and rejection properties of the prepared membranes were significantly enhanced by small addition of Brij‐58 surfactant in the casting solution along with using the lowest level of CBT. Addition of 4 wt. % of Brij‐58 and using cold coagulation bath resulted in the highest rejection of As (V). Initial increase in Brij‐58 concentration, from 0 wt. % to 2 wt. %, resulted in higher rejection of As (III). However, higher Brij‐58 concentrations than 2 wt. % (increase from 2 wt. % to 6 wt. %) led to lower rejection of As (III). Also, it was found out that addition of Brij‐58 in the casting solution along with increasing the CBT resulted in formation of membranes with high permeability and sub‐layer porosity and thin top layer. Copyright © 2012 John Wiley & Sons, Ltd.     

A Potentiometric Study of the Briggs–Rauscher Oscillatory Reaction in a Solution of Nonionic Surfactants and tert‐Butanol

The concentration effect of nonionic surfactants (Triton X‐100, Brij 30, Brij 58, Tween 20, and Tween 80) and tert‐butanol was investigated on the Briggs–Rauscher oscillatory reaction in a stirred batch reactor at 25 ± 0.1°C in both the absence and presence of nonionic surfactant and tert‐butanol as well. The addition of Triton X‐100, Brij 58, and Tween 20 influenced the oscillatory parameters in a similar fashion: a decrease of the induction period until its disappearance, an increase of the oscillation period, an increase of the oscillation amplitude, an increase of the duration of the oscillation, and a gradual increase of the oscillation numbers. The addition of Brij 30 has no significant effect on the oscillation parameters of the Briggs‐Rauscher oscillatory reaction. The effect of tert‐butanol on the Briggs–Rauscher oscillatory reaction is very similar to the effect of Brij 58; however, we were unable to observe the disappearance of the induction period on the studied concentration range. The addition of Tween 80 to the reaction mixture has a similar effect as the addition of Triton X‐100, Brij 58, or Tween 20, except for the induction period, which in the case of Tween 80, it becomes larger. The observed effects are explained in terms of micellar catalysis or inhibition, that is, in a different extent of individual reactants of solubilization.     

THE EFFECTS OF MIXED MICELLES OF SURFACTANTS ON POLYMERIZATION OF ACRYLAMIDE

The polymerization of acrylamide in mixed micellar solutions of surfactants, initiated by NaHSO₃ has been studied at 20 and 3Q° C with time variable method of thermokinetics for 1. 5-order reaction. The results indicate that the mixed micellar systems of cationic or anionic with zwitterionic surfactants (SLS/ CTAB, SLS/ TTAB, SLS/ SDS) and cationic with nonionic surfactants (Brij 357sol; CTAB, Bri-J35/TTAB, Brij35/ DTAB) have catalytic effect on the polymerization in the order, at 20° C. SLS/ SDS SLS/ TTAB SLS/ CTAB Brij35/ CTAB at 30° C SLS/ SDS SLS/ TTAB≈ / CTAB Bri-j35/ DTAB= sBrij35/ TTAB as Brij35/ CTAB, while Brij35/ SDS mixed micellar system has inhibition. These effects are attributed to the effect of the Stern layer of mixed micelles on the step of initiator (HSOT) to form free radical.