Self-Assembly Behavior of Benzotriazole in Water

The self-assembly behavior of ¹H-benzotriazole (BTA) in aqueous solutions below its solubility limit has been revealed for the first time using NMR and light scattering techniques. Relaxation time, diffusion and chemical shift NMR techniques in addition to various light scattering techniques were used to study the aqueous behavior of ¹H-Benzotriazole (BTA). These studies have revealed the self assembly of BTA molecules in water. Results show that BTA molecules tend to aggregate in water to form nanoparticles with radius in the range of 5 nm. The critical aggregation concentration (CAC) is estimated based on NMR data to be ～16–20 mM. Such a critical aggregation concentration is comparable with the typical critical micelle concentration (CMC) for surfactants that have moderate aqueous solubility. The self-assembly behavior of BTA may not be limited to benzotriazole. It might be generally true for all poorly water soluble species to aggregate at concentrations below their solubility.     

Luminescent properties of Tb3+ and Gd3+ ions doped aluminosilicate oxyfluoride glasses

Tb³⁺ and Gd³⁺ ions doped lithium–barium–aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Tb³⁺-doped lithium–barium–aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. The luminescence intensity of Tb³⁺ ion increases for those (Tb³⁺, Gd³⁺)-codoped glasses. Energy transfer process from Gd³⁺ ion to Tb³⁺ ion is indicated.     

NEW NON-IONIC SURFACTANTS FROM LYSINE AND THEIR PERFORMANCE

In this paper a new class of multichain non-ionic surfactants based on lysine with two octyl, decyl, dodecyl or tetradecyl chains and one polydispersed polyoxyethylene diethanolamide head group are introduced. Measurements at air/water interface and bulk solution of surface-active properties such as surface tension and critical micelle concentration were made. These compounds were obtained by condensation of the corresponding long chain N^α, N ^x diacyl lysine with a polydispersed oxyethylene diethanolamine which was prepared in our laboratory. A preliminary study of their water solubility properties is also described. The surface-active properties were evaluated by measuring the variation of surface tension and the formation of a presumable CMC as a function of concentration in the aqueous solution. All compounds were soluble in water up to 0.5% (w/v). They showed normal surface tension values in water solution and presented higher CMC than classical polyoxyethylene alcohols non ionic surfactants with the same number of carbon atoms in the hydrophobic moiety. In this series when each chain is increased by four methylene units, the CMC falls to about one-hundreth of its previous value.     

表面活性剂特性吸附对增强光敏分子固体为基极的光伏打效应的影响

卟啉类的光电极在分子固体液体接界光伏打电池工作中已得到研究。本文用阴离子型表面活性剂在固体表面上的特性吸附等温线来分析此种离子浓度对数函数与光伏打效应增长的关系,并研究了表面活性剂烷基链长、极性基、阳离子型表面活性剂及非离子型表面活性剂对光伏打效应增强的影响。内Helmholtz层结构与参量变化对光伏打效应也起重要作用。     

Removal of cadmium ions using micellar-enhanced ultrafiltration with mixed anionic-nonionic surfactants

Micellar-enhanced ultrafiltration (MEUF) was used to remove cadmium ions from wastewater efficiently. In this study the nonionic surfactants polyoxyethyleneglycol dodecyl ether (Brij35) and polyoxyethylene octyl phenyl ether (TritonX-100) were for micellar-enhanced ultrafiltration to lower the dosage of the anionic surfactant sodium dodecyl sulfate (SDS). The surfactant critical micelle concentration (CMC) and the degree of micelle counterion binding were investigated. The effects of nonionic surfactant addition on the efficiency of cadmium removal, the residual quantities of surfactant, the permeate flux and the secondary membrane resistance were investigated. A comparison between MEUF with SDS and MEUF with mixed anionic–nonionic surfactants was undertaken. The results show that the addition of Brij35 or TritonX-100 reduced the CMC of SDS and the degree of counterion binding for the micelles. Due to these variations the Cd²⁺ rejection efficiency was at a maximum when the Brij35:SDS and the TritonX-100:SDS molar ratio was 0.5. The Cd²⁺ rejection efficiency in MEUF with SDS is higher than for MEUF with mixed surfactants when the total dose of surfactant is constant. The permeate flux of MEUF with SDS is higher than that for MEUF with mixed surfactants while the secondary resistance of MEUF with SDS is less than that of MEUF with mixed surfactants.     

Phase behaviors of Gemini cationic surfactants/n-butanol/water systems

Phase diagrams for ternary system of the Gemini cationic surfactants, N,N-long chain alkyl-2-hydroxyl-N,N,N,N-tetramethyl diammonium dichloride (G_nCl₂) with butanol and water have been drawn based on experimental data at 25 °C. The phase diagrams show that L phase and different liquid crystalline phases are existent in the ternary system at different components. Electric conductivity of the L phase has been studied. Small-angle X-ray scattering (SAXS), ²H (deuterium) quadrupolar splitting (²H NMR) and the polarizing-light microscope were employed to confirm the characteristic texture structures and the microstructure of three different liquid crystalline phases.     

SDS及其与十二烷基三乙基溴化铵混合体系在矿化水中的表面活性

测定了十二烷基硫酸钠(SDS)、十二烷基三乙基溴化铵(DTEAB)单一体系及不同摩尔比的混合体系在矿化水溶液中的表面活性,并与在纯水和NaCl水溶液中的表面活性作了比较．所得结果表明：(1)阴离子表面活性剂SDS在含Ca^2 ,Mg^2 等的矿化水中有比在纯水和NaCl水溶液中更好的表面活性．这一方面是由于矿化水中的Ca^2 ,Mg^2 对负电胶团和表面吸附层的强烈电性作用,另一方面在大量Na^ 存在时,钠钙盐混合表面活性剂Krafft点提高不多;(2)SDS和DTEAB混合物在矿化水中具有很强的增效作用,其表面活性的变化规律与在纯水和NaCl水溶液中基本相同,表明阴阳离子表面活性剂混合体系具有优异的抗矿化水性能．这些结果可用阴、阳表面活性离子的电性作用解释．     

A critical assessment of capillary condensation and evaporation equations: a computer simulation study

Nonaqueous reverse micelles of brij surfactants are prepared in benzene and ethylammonium nitrate (EAN). The effect of polar head group bulk on reverse micellar size was studied with brij-52, brij-56 and brij-58 whereas the effect of polarity of hydrocarbon chain was investigated taking brij-52 and brij-93 with varying W(s) (W(s)=[EAN]/[surfactant]). Dynamic light scattering (DLS) has been employed to reveal the size and shape of the reverse micelles. Micropolarities of these reverse micelles were investigated by visible spectroscopy using methylene blue (MB) and methyl orange (MO) as molecular optical probes. It has been revealed from the experimental results that with increase in polar head group size reverse micellar size increases. Moreover, it is also observed that with increasing polarity of the hydrocarbon chain the average size of the reverse micelles decreases. It can be concluded that polar head group size and polarity of hydrocarbon chain play important roles in determining reverse micellar size of the brij surfactants apart from the W(s) ratio, nature of the solvent medium, and concentration of the surfactants.     

杂双子表面活性剂的研究进展

分子结构对称的gemini 表面活性剂是通过联接链将两个相同头基和相同烷烃链的普通表面活性剂在头基或靠近头基处以化学键方式联接在一起,这种表面活性剂产生了新颖且复杂的自组织行为,引起人们的高度关注。但由于合成上的困难,迄今为止较少研究分子结构不对称的gemini 表面活性剂(又称为杂双子表面活性剂,heterogemini surfactant) 。初步研究显示heterogeminis 在分子自组织过程中具有更多可调控的分子结构因素,获得了某些新颖的结果,例如明显增大了自组织过程的焓驱动力,正-负离子头基分子构成了无反离子的体系,长-短烷烃主链分子成功地将形成的囊泡串接起来等。本文综述当前的研究进展,并提出某些潜在的研究意义。     

Surfactant polymer interactions between strongly interacting cationic surfactants and anionic polyelectrolytes from conductivity and turbidity measurements

The interactions between oppositely charged surfactant/polymer mixtures have been studied using conductivity and turbidity measurements. The dependence of aggregation phenomenon on the chain length and head group modifications of conventional cationic surfactants, i.e., hexadecyl- (HTAB), tetradecyl- (TTAB), and dodecyltrimethylammonium bromides (DTAB) and dimeric cationic surfactants, i.e., decyl- (DeDGB) and dodecyldimethylgemini bromides (DDGB), is investigated. It was observed that cationic surfactants induce cooperative binding with anionic polyelectrolytes at critical aggregation concentration (cac). The cac values are considerably lower than the critical micelle concentration (cmc) values for the same surfactant. After the complete complexation, free micelles are formed at the apparent critical micelle concentration (acmc), which is slightly higher in aqueous polyelectrolyte than in pure water. Among the conventional and dimeric cationic surfactants, DTAB and DeDGB, respectively, have been found to have least interactions with oppositely charged polyelectrolytes.     

Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg²⁺ detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb³⁺ from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg²⁺ into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg²⁺. As a kind of Hg²⁺ nanosensor, the probe exhibited excellent selectivity for Hg²⁺ and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg²⁺ in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging.     

混合反胶束的电导与微结构研究

反胶束是两亲分子在非极性溶剂中形成的一种有序组合体，在医药、化工、采油、胶束催化及酶催化等领域中有重要应用．与胶束溶液相比，人们对反胶束的形成与结构的了解至今仍不充分．特别是对于由混合表面活性剂形成的反胶束的研究几乎无人涉及．本文采用动态光散射、电导及荧光光谱等手段对阴离子表面活性剂AOT与非离子表面活性剂形成的混合反胶束进行了研究，旨在探讨利用表面活性剂的复配来调节和控制反胶束的结构和性能．亚实验部分二异辛基磺化琉璃酸钠（AOT，Sigma公司）；Brij30为含4个氧乙烯基（EO基）的十二碳醇（AcrosOrgani…     

Structural Parameters of Mixed Nonionic Surfactants Microemulsions

In this study, we estimated the structural parameters of water/mixed nonionic surfactants/R (+)-limonene microemulsions. The mixed surfactants are sucrose laurate and ethoxylated mono-di-glyceride. U-type microemulsion region was observed in these systems. It was found that changes in the surfactants mixing ratio, surfactants contents and oil/water weight ratio in the microemulsions incite a considerable change in the aggregation number, core radius and interfacial area per mixed surfactants head groups in the formed microemulsions. The interfacial area per mixed surfactant head groups increases while the aggregation number decreases with the increase in the ethoxylated mono-di-glyceride mass fraction in the mixed surfactants. The For an oil/water weight content equals unity, the interfacial area per mixed surfactants head groups is constant for mixed surfactants contents below 35 wt%. For mixed surfactants contents above 35 wt% the interfacial area per mixed surfactants head groups decrease and stabilizes at the lower value. The aggregation number decreases with the increase in the mixed surfactants contents. The aggregation number decreases also with the increase in the oil/water weight ratio at fixed mixed surfactants content.     

添加剂对非离子十二烷基聚氧乙烯聚氧丙烯醚浊点的影响

测定了无机盐、单元及多元醇、有机酸及离子型表面活性剂对3种非离子表面活性剂十二烷基聚氧乙烯聚氧丙烯醚C₁₂H₂₅(EO)_m(PO)_nH(LS₃₆,m=3,n=6;LS45,m=4,n=5;LS54,m=5,n=4)浊点的影响.     

Synthesis and unusual properties of novel alkylbenzene sulfonate gemini surfactants

Seven new dialkyldibenzene disulfonate gemini surfactants have been synthesised. The physico-chemical properties such as their surface tensions, krafft temperatures and melting temperatures have been measured. It was found that the anionic gemini surfactants showed some aberrant properties. The results determined by drop-volume method indicated that surfactants Id, Ie at 25 °C and IIb at 50 °C showed no cmc and lowered surface tension of water hardly despite their seemingly favorable amphiphilic components. However, the three surfactants showed a sharp cmc and good surface activity with the increment of temperature. Surfactant Ie with two longer chains had a higher cmc than that for shorter chain surfactant Id. Furthermore, for this class of anionic gemini surfactants, the spacer carbon number had more important effects than the alkyl chain carbon number on their krafft temperatures and melting temperatures.     

Synthesis and mesophases of glycerate surfactants

In the quest to rationally design novel mesophase systems the challenge remains to deconvolute the relationship between structure, composition, and function. In the current study, novel glycerol-derived surfactants with high negative interfacial areas and a preference for inverse phase behavior have been targeted and synthesized. This has been achieved by application of the rule-of-thumb afforded by the critical packing parameter (CPP), namely, that inverse phase behavior is favored by wedge-shaped molecules with relatively small head group versus chain volume. Highly splayed hydrophobes with exaggerated cross section such as oleyl (cis-octadec-9-enyl) hexahydrofarnesyl (3,7,11-trimethyl-dodecyl) and phytanyl (3,7,11,15-tetramethyl-hexadecyl) were particularly successful for this purpose across many variations of head group. The phase behavior of the binary system in water of many of these surfactants is relatively simple. Typically, cubic or inverse hexagonal phases exist at the interface with water with the inverse micellar phases present at lower hydration. The inverse liquid crystalline phases were present for a broad range of temperatures and compositions.     

Synthesis of nanocrystalline calcium phosphate in microemulsion--effect of nature of surfactants

Nanosized calcium phosphate (CP) powders have been synthesized by an inverse microemulsion system using kerosene as the oil phase, a cationic surfactant Aliquat 336, a non-ionic surfactant Tween 20 and their mixture and aqueous solutions of calcium nitrate tetrahydrate and biammonium hydrogen phosphate as the water phase. It has been found that the nature of surfactants played an important role to regulate the size and morphologies of the calcium phosphate nanoparticles. The cationic surfactant Aliquat 336 has been found to regulate the nucleation and crystal growth. The synthesized powders have been comprehensively characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Our results show that the brushite (DCPD) is the major phase comprising the calcium phosphate nanoparticles. In mixed surfactants mediated system a morphological controlled highly crystalline particles have been synthesized. Further, the role of Aliquat 336 has been established and a plausible synthetic mechanism has been proposed.     

Spectroscopic studies on the interaction of cilostazole with iodine and 2,3-dichloro-5,6-dicyanobenzoquinone

Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln³⁺). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb³⁺–FQ and Eu³⁺–FQ complexes have been investigated in this contribution. Ce⁴⁺–SO₃²⁻ in acidic conditions was taken as the CL system and sensitized CL intensities of Tb³⁺–FQ and Eu³⁺–FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb³⁺–FQ complexes show characteristic peaks of Tb³⁺ at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb³⁺–ENX, Tb³⁺–NFLX, Tb³⁺–LMFX and Tb³⁺–FLRX display relatively strong emission intensity compared with Tb³⁺–OFLX, Tb³⁺–RFX, Tb³⁺–GFLX and Tb³⁺–SPFX. Quite weak peaks with unique characters of Eu³⁺ at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu³⁺–ENX, but no notable sensitized luminescence and CL of Eu³⁺ could be observed when Eu³⁺ is added into other FQ. The distinct differences on emission intensity of Tb³⁺–FQ and Eu³⁺–FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln³⁺. The different sensitized luminescence and CL signals among Tb³⁺–FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb³⁺–FQ and Eu³⁺–FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results.     

Lyotropic liquid crystal phase behaviour of the zwitterionic surfactants 4-n-tridecyl- and 4-n-heptadecyl-pyridinium N-oxide in water

The phase behaviour, liquid crystal structures and head group hydration of two 4-n-alkylpyridine-N-oxide surfactants have been studied using optical microscopy, DSC and ²H NMR spectroscopy. Only a limited swelling of the surfactant phase occurs in water, so that no micellar solution phase (L₁) occurs. The lamellar phase is the only mesophase observed. Water (²H) quadrupole splittings indicate that the head group binds c. 6 water molecules.     

The Dynamics and Energetics of Percolation of Water/AOT/Isooctane Microemulsions upon the Addition of Tween Nonionic Surfactants

The temperature‐induced percolation of water/AOT/isooctane microemulsions was studied in the presence of the Tween series of polyoxyethylated nonionic surfactants employing conductometry. Percolation temperatures were determined utilizing the Sigmoidal‐Boltzmann equation procedure. The results were analyzed in terms of the percolation temperature, scaling parameters, activation energy, and thermodynamics of the clustering process. It was observed that the Tween series of surfactants aided the percolation process, and the percolation parameters were found to be independent of the hydrophobic chain length of these additives. The percolation temperature was found to be dependent on the concentration of the Tweens. It was concluded that the influence of the Tween series of surfactants on the percolation phenomenon was due to the number of ethylene oxide moieties in the head groups region of the additive. The effects of these additives was described in terms of modifications in the microemulsion's interfacial layer, outer oil layer, viscosity of the water micropool, and interactions between the anionic head groups of AOT.