Optical sensor of anionic surfactants using solid-phase extraction with a lactone-form rhodamine B membrane.

An optical sensor for the detection of anionic surfactants was developed. The optical sensing membrane is a 2-nitrophenyloctyl ether-plasticized poly(vinyl chloride) membrane incorporating a lactone-form Rhodamine B (L-RB). The response of the optical membrane to anionic surfactants was a result of the ion-pair coextraction of an anionic surfactant and a proton into the PVC membrane. The L-RB forms an ion associate with the extracted anionic surfactant; simultaneously, the formed L-RB ion associate is accompanied by a spectral change. Namely, the extracted anionic surfactant changes the color of the membrane from light pink to dark pink (absorption maximum; 558 nm). The optical membrane responds to anionic surfactants, such as dodecylbenzenesulfonate, dodecylsulfate and di-2-ethylhexyl sulfosuccinate in the concentration range from 1 to 50 microM.     

Hexacyanoferrate-intercalated nickel zinc hydroxy double salts

When anionic clay like nickel zinc hydroxyacetate was subjected to anion exchange reaction with either hexacyanoferrate(II) or hexacyanoferrate(III) ions, the complex anion intercalation was accompanied by auto redox reactions. In both the cases a mixture of hexacyanoferrate(II) and hexacyanoferrate(III) ions was found to be intercalated in the anionic clay. The mixed anion intercalated anionic clays could be oxidized by hydrogen peroxide to get pure hexacyanoferrate(III) intercalated anionic clay. Thermal decomposition of the intercalated anionic clays yields mixed oxides of Ni, Zn and Fe.     

Radiation-induced grafting polymerization by the anionic mechanism

The radiation-induced grafting polymerization of phenylacetylene and 2-methyl-5-vinylpyridine (2M-5VPy) onto low-density polyethylene has been investigated under strict identical conditions, using crude and thoroughly dried monomers. In the case of thoroughly dried monomers, the radiation-induced grafting is performed by the combined (radical + anionic) mechanism. The kinetics of radical and anionic grafting of 2M-5VPy are investigated in detail. The activation energies are 4.8 ± 0.3 and ?2.7 ± 0.3 kcal/mole for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to the dose rate to the 0.47 ± 0.03 and 0.92 ± 0.03 power for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to monomer concentration to the 1.55 ± 0.05 and 2.1 ± 0.05 power for the radical and anionic grafting, respectively. These data conform to the contribution of the anionic mechanism in a thoroughly dried system. The mechanism of radiation-induced anionic grafting is discussed.     

阻滞阴离子聚合的研究进展

介绍了阻滞阴离子聚合引发剂体系近十年的研究现状,详细讨论了几代阻滞引发体系各自的阻滞机理,以及在阴离子聚合制备苯乙烯共聚物树脂中的应用。简单介绍了BASF公司应用阻滞阴离子聚合制备高抗冲聚苯乙烯的应用现状,指出了阻滞阴离子聚合活性可控的优点使其具有更广泛的发展空间。     

以阴离子表面活性剂/阳离子聚铵复合胶束为模板合成有序介孔二氧化硅

基于静电作用, 阴离子表面活性剂可与阳离子聚铵组装形成复合胶束. 借助阳离子聚铵,复合胶束可以作为模板与硅源协同组装, 形成高度有序的介孔二氧化硅. 本文通过调变不同种类阴离子表面活性剂、合成体系pH值、合成温度及阳离子聚铵和硅源用量等因素, 合成了具有不同介观结构和形貌的介孔二氧化硅. 实验证实阴离子表面活性剂/阳离子聚铵复合胶束模板法是合成介孔二氧化硅的一种通用方法.     

Interaction between β‐Cyclodextrin and Mixed Cationic‐Anionic Surfactants (2): Aggregation Behavior

The interactions between β‐cyclodextrin (β‐CD) and the mixtures of cationic‐anionic surfactants in the aqueous solution were investigated by surface tension, rheology, and dynamic light scattering measurements. It was shown that the key‐lock interactions between β‐CD and mixed cationic‐anionic surfactants were stronger than the electrostatic/hydrophobic interactions between cationic and anionic surfactants. The inclusion of β‐CD to surfactants could destroy the ion‐pair and aggregates of cationic‐anionic surfactants, and even inhibited the precipitation of the mixed cationic‐anionic surfactants. Furthermore, the inclusion of β‐CD to surfactants could also destroy the hydrogen bond between β‐CD molecules, inducing the disassociation of the aggregation formed by β‐CD themselves.     

Anionic ligand effect on the nature of epoxidizing intermediates in iron porphyrin complex-catalyzed epoxidation reactions

We have studied an anionic ligand effect in iron porphyrin complex-catalyzed competitive epoxidations of cis- and trans-stilbenes by various terminal oxidants and found that the ratios of cis- to trans-stilbene oxide products formed in competitive epoxidations were markedly dependent on the ligating nature of the anionic ligands. The ratios of cis- to trans-stilbene oxides obtained in the reactions of Fe(TPP)X (TPP = meso-tetraphenylporphinato dianion and X(-) = anionic ligand) and iodosylbenzene (PhIO) were 14 and 0.9 when the X(-) of Fe(TPP)X was Cl(-) and CF(3)SO(3)(-), respectively. An anionic ligand effect was also observed in the reactions of an electron-deficient iron(III) porphyrin complex containing a number of different anionic ligands, Fe(TPFPP)X [TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion and X(-) = anionic ligand], and various terminal oxidants such as PhIO, m-chloroperoxybenzoic acid (m-CPBA), tetrabutylammonium oxone (TBAO), and H(2)O(2). While high ratios of cis- to trans-stilbene oxides were obtained in the reactions of iron porphyrin catalysts containing ligating anionic ligands such as Cl(-) and OAc(-), the ratios of cis- to trans-stilbene oxide were low in the reactions of iron porphyrin complexes containing nonligating or weakly ligating anionic ligands such as SbF(6)(-), CF(3)SO(3)(-), and ClO(4)(-). When the anionic ligand was NO(3)(-), the product ratios were found to depend on terminal oxidants and olefin concentrations. We suggest that the dependence of the product ratios on the anionic ligands of iron(III) porphyrin catalysts is due to the involvement of different reactive species in olefin epoxidation reactions. That is, high-valent iron(IV) oxo porphyrin cation radicals are generated as a reactive species in the reactions of iron porphyrin catalysts containing nonligating or weakly ligating anionic ligands such as SbF(6)(-), CF(3)SO(3)(-), and ClO(4)(-), whereas oxidant-iron(III) porphyrin complexes are the reactive intermediates in the reactions of iron porphyrin catalysts containing ligating anionic ligands such as Cl(-) and OAc(-).     

催化动力学光度法测定阴离子表面活性剂

基于在H2SO4介质中,阴离子表面活性剂对高碘酸钠氧化罗丹明B褪色的反应具有较强的催化作用,建立了测定阴离子表面活性剂的催化动力学光度法.本文以十二烷基硫酸钠为标准品进行实验,线性范围为0.08～0.20 mg/L,检出限为0.0193 mg/L.用于水样中阴离子表面活性剂总量的测定,测定结果的相对标准偏差为1.3%～1.4%,回收率为104%～106%.     

Effect of polyelectrolytes and polyelectrolyte mixtures on the electrokinetic potential of dispersed particles. 2. Electrokinetic potential of silica particles in electrolyte, polyelectrolyte and polyelectrolyte mixtures solutions

The effect pH, ionic strength (KCl concentration), weakly and medium charged anionic and cationic polyelectrolytes (PEs) as well as their binary mixtures on the electrokinetic potential of silica particles as a function of the polyelectrolyte/mixture dose, its composition, charge density (CD) of the PE, and way of adding the polymers to the suspension has been studied. It has been shown that addition of increasing amount of anionic PEs increases the absolute value of the negative zeta-potential of particles at pH > pH isoelectric point (IEP = 2.5); this increase is stronger the charge density of the polyelectrolyte is higher. Adsorption of cationic polyelectrolytes at these pH values gives a significant decrease in the negative ζ-potential and overcharging the particles; changes in the ζ-potential are more pronounced for PE samples with higher CD. In mixtures of cationic and anionic PE at pH > pHIEP, the ζ-potential of particles is determined by the adsorbed amount of the anionic polymer independently of the CD of PEs, the mixture composition and the sequence of addition of the mixture components. Unexpectedly, the ζ-potential of silica at pH = 2.1, i.e. < pHIEP, turned out to be positive in the presence of both anionic PE and cationic + anionic PE mixtures. This is explained by formation (and adsorption onto positively charged silica surface) of pseudo-cationic PEs from anionic ones due to transfer of protons from the solution to the amino-group of the anionic polymer. Considerations about the role of coulombic and non-coulombic forces in the mechanism of PE adsorption are presented.     

A family of single-isomer,sulfated gamma-cyclodextrin chiral resolving agents for capillary electrophoresis: octa(6-O-sulfo)-gamma-cyclodextrin

The second member of the single-isomer, sulfated gamma-cyclodextrin family, the sodium salt of octa(6-O-sulfo)-gamma-cyclodextrin (OS) has been synthesized, characterized and used to separate the enantiomers of nonelectrolyte, acidic, basic, and ampholytic analytes by capillary electrophoresis in acidic aqueous background electrolytes. The anionic effective mobilities of the nonelectrolyte and anionic analytes increased with increasing concentration of OS. The effective mobilities of strongly complexing cationic analytes became anionic with very low OS concentrations and passed local anionic effective mobility maxima as the OS concentration, and along with it, the ionic strength, of the background electrolyte increased. The effective mobilities of the weakly binding cationic analytes became only slightly anionic at high OS concentration values and did not show the local anionic effective mobility maxima. For nonelectrolyte analytes, separation selectivities decreased with increasing OS concentration. For cationic analytes, separation selectivities were highest where the effective mobilities of the less mobile enantiomers approached zero. OS proved to be a broadly applicable chiral resolving agent.     

Electrokinetic potential of bentonite and kaolin particles in the presence of polymer mixtures

In order to elucidate the mechanisms of flocculation by polymer mixtures, the effect of adsorption of non-ionic poly(ethylene oxide) — PEO, two samples of strongly (SNF FO 4800) and medium charged (SNF FO 4350) cationic and two samples of medium (SNF AN 935) and weakly charged (SNF AN 905) anionic polyelectrolytes (PE) as well as their binary mixtures on the electrokinetic potential of bentonite and kaolin particles has been studied. It is shown that in the presence of PEO-anionic/cationic polymer mixture, the electrokinetic potential of particles is determined by the adsorption of the polyelectrolyte; neither cationic nor anionic segments can be displaced by the non-ionic polymer. In mixtures of cationic and anionic polyelectrolytes, the ζ-potential of particles is determined by the adsorbed amount of anionic polymer independently of the charge density of PE and way of addition of the mixture components to the suspension, i.e. (1) first adding the cationic polymer, then the anionic one, or (2) first adding the anionic polymer then the cationic one, or (3) adding an increasing amount of pre-prepared 1: 1 mixture. The highest absolute ζ-potential values are observed for pH 7.5 when the surface of bentonite or kaolin particles is “purely” negatively charged and the anionic PE layer is most extended because of few contacts to the surface. With decreasing the pH, the (negative) ζ-potential of particles decreases due to appearance of a small amount of positive charges on the surface that bond an increasing amount of negative segments and results in shrinking of the adsorbed layer of the anionic PE. It is shown also that the electrokinetic potential of particles in anionic and cationic PE mixtures at all studied pH (4, 5, and 7.5) depends on the spatial distribution of negatively charged segments near the surface. The regularities observed are explained by formation of long loops and tails of anionic segments on the surface because of the small number of contacts to the surface; the cationic polyelectrolyte forms on the surface a thin layer with a big number of contacts and which is hidden behind the more extended anionic polymer layer.     

Needle-like supramolecular amphiphilic assembly constructed by the host–guest interaction between calixpyridinium and methotrexate disodium

In this work, the host–guest interaction between calixpyridinium and the anionic anticancer drug methotrexate disodium was explored in water. Unexpectedly, an interesting anisotropic needle-like rather than an ordinary isotropic spherical supramolecular amphiphilic assembly was fabricated by the complexation of calixpyridinium with methotrexate disodium. It is the second anionic guest to be discovered to form the non-spherical supramolecular assembly upon complexation with calixpyridinium. This discovery implies the possibility to construct various topological nanostructures based on the host–guest interactions between calixpyridinium and the anionic drugs in the future. The resulting calixpyridinium–drug assemblies with different morphologies may have the diverse potentials to adjust the efficacies of anionic drugs.     

Aminocalix[4]arene: the effect of pH on the dynamics of gate and portals on the hydrophobic cavity

The pH of a solution shows a significant effect on the dynamics of the gate (formed by eight benzylic functions) and portal on the hydrophobic cavity of receptor. At pH 5.8 the gate closes and prohibits the entry of anionic guests. However, at pH 7.3 the gate opens and allows the entry of anionic guests into the hydrophobic cavity. It is the first time that anionic receptor efficiently recognizes anionic guests.     

阴(负)离子聚合二十年

近20多年负离子聚合在新引发剂体系、新单体开发以及聚合理论方面均取得了进展,出现了配伍负离子聚合LAP、阻滞负离子聚合RAP等概念。实现了对聚合物结构、聚合动力学的进一步控制。在工业方面,负离子聚合生产规模和产品应用范围扩大,同时也开发出多种新产品,如集成橡胶、负离子合成的高抗冲聚苯乙烯等国内的负离子产品开发十分迅速在加氢型负离子聚合产品方面还取得了突破性发展     

Characterization and Aggregation Behaviors of Mixed DDAB/SDS Solution With and Without Poly(4-styrenesulfonic Acid-Co-Maleic Acid) Sodium

Synthetic vesicles are formed by cationic and anionic surfactants, didodecyldimethylammonium bromide (DDAB), and sodium dodecylsulfate (SDS). The morphology, size, and aqueous properties of cationic/anionic mixtures are investigated at various molar ratios between cationic and anionic surfactants. The charged vesicular dispersions made of DDAB/SDS are contacted or mixed with negatively charged polyelectrolyte, poly(4-styrenesulfonic acid-co-maleic acid) sodium (PSSAMA), to form complexes. Depending on DDAB/SDS molar ratio or PSSAMA/vesicle charge ratio, complexes flocculation or precipitation occur. Characterization of the cationic/anionic vesicles or complexes formed by the catanionic vesicles and polyelectrolytes is performed by transmission electron microscope (TEM), dynamic light scattering (DLS), conductivity, turbidity, and zeta potential measurements. The size, stability, and the surface charge on the mixed cationic/anionic vesicles or complexes are determined.     

钛酸四丁酯水解制备聚苯乙烯/二氧化钛核壳粒子及空心二氧化钛微球

通过无皂乳液聚合方法制备了阳离子型及阴离子型聚苯乙烯(PSt)乳胶粒,并对后者用γ-氨丙基三乙氧基硅烷(KH550)进行了表面改性制得了乳胶粒表面载正电荷的乳液.在乙醇与水的混合溶剂中,分别使用以上3种PSt乳胶粒为核加入钛酸四丁酯制备了核壳型PSt/TiO2复合粒子.结果显示,仅在使用经KH550改性的阴离子PSt乳...     

Electric Conductivity of Sandwich Structures with Films of Poly-N-epoxypropylcarbazole Doped with Organic Dyes of Various Ionicity

The conducting characteristics of samples of a sandwich structure with films based on the photoconducting polymer poly-N-epoxypropylcarbazole doped with cationic, anionic, cationic–anionic, neutral, and bipolar organic dyes were investigated. It was shown that the conductivity of the samples is caused by ion drift, thermofield generation of holes from uncontrollable impurity centers, thermofield generation of electrons and holes from the dopant molecules, and thermofield injection of electrons and holes from the electric contacts. The contribution from the injection currents of the charge carriers increases in the transition from a cationic dye to anionic, cationic–anionic, and intraionic dyes.     

Chiral separation of anionic and neutral compounds using a hepta-substituted cationic beta-cyclodextrin as a chiral selector in capillary electrophoresis

Enantiomeric separations of six anionic and two neutral racemates were achieved using a fully substituted heptakis(6-hydroxyethylamino-6-deoxy)-beta-cyclodextrin (beta-CD-EA) as a chiral selector. As beta-CD-EA provides a dynamic coating on the capillary wall, reverse-polarity capillary electrophoresis (CE) configuration is applied for separations of anionic and neutral chiral compounds. Chiral separations of various classes of anionic and neutral enantiomers were found to be highly dependent on pH because the degree of protonation of beta-CD-EA can alter the shape of the CD cavity by charge repulsion, altering complexation, aiding selectivity, and leading to better enantiomeric separation. In general, the chiral resolution of anionic enantiomers was enhanced at higher pH. This suggests that carboxylate or phosphate groups on the analyte may interact with the protonated amine groups of cationic CD. The successful enantioseparation was achieved in a pH range of 6.6-7.8 for all six anionic analytes, in the presence of 10 mM beta-CD-EA.     

Assessment of the surfactant-dye binding degree method as an alternative to the methylene blue method for the determination of anionic surfactants in aqueous environmental samples

The surfactant to dye binding degree (SDBD) method is proposed for the routine monitoring of anionic surfactants in aqueous environmental samples and their analytical features compared with those provided by the standard methylene blue (MB) method. This new analytical approach is based on the effect that anionic surfactants exert on the binding degree of the cationic surfactant didodecyldimethylammonium bromide (DDABr) to the anionic dye Coomassie Brilliant Blue G (CBBG). The formation of DDABr-CBBG aggregates is monitored photometrically. The analytical applicability of the proposed method was demonstrated by determining anionic surfactants in tap, river and swamp water, and raw and treated sewage. The mean recoveries obtained ranged between 99 and 101%. The SDBD method offers important advantages over the classical MB method: it is more sensitive, selective, precise, simple and rapid; the analytical response is independent of the molecular structure of the anionic surfactants, and the volume of sample required for analysis and the consumption of organic solvents are significantly reduced.     

Role of ion pairing in anionic additive effects on the separation of cationic drugs in reversed-phase liquid chromatography

Mobile phase additives can significantly affect the separation of cationic drugs in reversed-phase liquid chromatography (RPLC). Although there are many applications for anionic additives in RPLC separations, the retention mechanism of basic drugs in the presence of inorganic and highly hydrophilic anionic species in the mobile phase is not at all well understood. Two major retention mechanisms by which anionic additives can influence the retention of cations are: (1) ion pair formation in the mobile phase with subsequent retention of the neutral ion pair; (2) pre-sorption of anionic additives on the stationary phase followed by "dynamic ion-exchange" or "electrostatic interaction" with the analytes. Because the use of ion pair chromatography in the separation of proteins, peptides, and basic drugs is rapidly increasing, understanding the retention mechanism involved is becoming more important, especially for the smaller commonly used hydrophilic anionic additives (e.g., formate HCOO, chloride Cl-, trifluoroacetate CF3COO-, perchlorate ClO4-, and hexafluorophosphate PF6-). In this work, we compared various anionic additives in light of their effects on the retention of basic drugs. As did many others we found that the addition of anionic additives (Cl-, CF3COO-, ClO4-, PF6-) profoundly influences the retention of basic drugs. In order to explain the data and differentiate the mechanisms by which the anionic additives perturb the chromatography, we used ion pair formation constants independently measured by capillary electrophoresis (CE) under the mobile phase conditions (pH, solvent composition) identical to those used in chromatography. Agreement between the predicted and experimental chromatographic data under various conditions was evaluated. Under specific circumstances (e.g., pH, stationary phase, and nature of anionic additive), we conclude that the ion pair mechanism is more important than the dynamic ion-exchange and at other conditions it remains a significant contribution.