Design and fabrication of electrospun polyethersulfone nanofibrous scaffold for high‐flux nanofiltration membranes

A novel class of high‐flux and low‐fouling thin‐film nanofibrous composite (TFNC) membranes, containing a thin hydrophilic top‐layer coating, a nanofibrous mid‐layer scaffold and a non‐woven microfibrous support, has been demonstrated for nanofiltration (NF) applications. In this study, the issues related to the design and fabrication of a polyethersulfone (PES) electrospun nanofibrous scaffold for TFNC NF membranes were investigated. These issues included the influence of solvent mixture ratio, solute concentration, additives, relative humidity (RH), and solution flow rate on the morphology of an electrospun PES nanofibrous scaffold, the distribution of fiber diameter, the adhesion between the PES scaffold and a typical poly(ethylene terephthalate) (PET) non‐woven support, as well as the tensile properties of the nanofibrous PES/non‐woven PET composite substrates. Uniform and thin nanofibrous PES scaffolds with strong adhesion to the nanofiber‐PET non‐woven are several of the key parameters to optimize the NF performance of TFNC membranes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2288–2300, 2009     

A composite polyaniline/graphene–coated polyamide6 nanofiber mat for electrochemical applications

In this study, polyamide6 (PA6) nanofiber mats were fabricated through the electrospinning process. The nanofibers were coated by polyaniline (PANI) using the in situ polymerization of aniline in the presence of graphene oxide. The composite of the PANI/graphene oxide–coated nanofiber mat was treated with hydrazine monohydrate to reduce graphene oxide to graphene, and this was followed by the reoxidation of PANI. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), thermal gravimetric analysis (TGA), tensile strength tests, electrical conductivity measurements, cyclic voltammetry (CV), and charge/discharge measurements were conducted on the composite PA6/graphene nanofiber mats. It was found that the surface of the PA6 nanofibers was coated uniformly with the granular PANI and graphene oxide. Besides, the composite nanofibers showed good tensile and thermal properties. Their electrical conductivity and specific capacitance, when used as a separator in the cell, were 1.02 × 10^?4 S/cm and 423.28 F/g, respectively. Therefore, the composite PANI/reduced graphene oxide–coated PA6 nanofiber mats could be regarded as suitable candidates for application in energy storage devices.     

Preparation and characterization of modified polyphenylsulfone membranes with hydrophilic property for filtration of aqueous media

In the present research, the low water flux of polyphenylsulfone membranes was addressed, and a novel improvement in their water permeation and fouling resistance was achieved using polyethylene glycol (PEG) as the hydrophilic additive. Scanning electron microscopy and field emission scanning electron microscopy, atomic force microscopy, attenuated total reflection Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and tensile test were applied for the investigation of membrane morphology, surface topography, surface chemical structure, thermal stability, and mechanical properties, respectively. Moreover, the relative hydrophilicity/hydrophobicity of the membranes was assessed via determination of membrane water uptake capacity and water contact angle. The membrane performance was studied and compared by determination of pure water flux and filtration of canned beans production wastewater as well as bovine serum albumin solution. The filtration results indicated a remarkable pure water flux and 100% turbidity rejection provided by the polyphenylsulfone/PEG 20 000 membrane. In addition, it was confirmed that the amount of residual PEG within the membrane was increased with increasing PEG molecular weight and concentration.     

The influence of protein aggregates on the fouling of microfiltration membranes during stirred cell filtration

Although macromolecular fouling of microfiltration membranes is one of the critical factors governing the performance of these filtration processes, there is still little fundamental understanding of the underlying phenomena that influence the initiation, rate, and extent of fouling. We have obtained experimental data for the flux decline during the stirred cell filtration of different commercial preparations of bovine serum albumin (BSA) through asymmetric polyethersulfone microfiltration membranes. The fouling characteristics of these commercial solutions varied substantially, with the flux decline directly related to the technique utilized to initially precipitate and prepare the BSA. Prefiltration of BSA solutions prior to microfiltration substantially reduced their fouling tendency, with the degree of improvement increasing as the prefiltration was performed through smaller molecular weight cut-off membranes. The protein solutions were also characterized using gel permeation chromatography (GPC), with the fouling tendency of the different BSA preparations highly correlated with the concentration of BSA dimers and other high molecular weight species present in these BSA solutions. These results suggest that BSA fouling of these microfiltration membranes is associated with the deposition of trace quantities of aggregated and/or denatured BSA, with these fouling species serving as initiation sites for the continued deposition of bulk protein.     

Fabrication and electrochemical instrumentation of redox‐active nanofiber mat for polyaniline incorporated with poly(imide sulfonate)

In this study, we demonstrate the fabrication of an electrochemically active nanofiber mat that is a composite of high‐performance poly(imide sulfonate) (PIS) and polyaniline (PANI). First, a nonconductive nanofiber mat comprising nanofibers having diameters of ca. 300 nm was fabricated by the electrospinning of ionomeric PIS in N,N‐dimethylformamide (DMF). Then, the nanofibers were modified using PANI, which was synthesized by the oxidative polymerization of aniline, yielding an electrochemically active nanofiber mat having a diameter of ca. 350 nm. It was confirmed that PANI was successfully incorporated onto the PIS nanofiber mats by X‐ray photoelectron spectroscopy. Subsequently, we conducted electrochemical measurements of the PANI‐modified nanofiber mats using a tailor‐made attachment in which the working electrode gently comes in contact with the nanofiber mat surface. This attachment was observed to be widely useful in the cyclic voltammetry measurements related to redox‐active nanofibers. These observations are expected to contribute to the advancements in application development of the electrochemically active nanofiber mats.     

Experimental study of a dynamic filtration system with overlapping ceramic membranes and non-permeating disks rotating at independent speeds

In a previous paper [Ding et al., J. Membr. Sci. 276 (2006) 232], we have investigated the performance in microfiltration of mineral suspensions of a novel filtration pilot consisting in overlapping ceramic membranes disks rotating at same speed on two parallel shafts. In this paper, we investigate a modification of this concept in which the ceramic disks of one shaft were replaced by non-permeating metal disks of same size rotating at a speed different from that of membranes. We also operated the pilot without disks on the 2nd shaft in order to eliminate membrane overlapping. When using metal disks with radial vanes, permeate fluxes were found to be 50–60% higher than those obtained in the same conditions with the previous design using only ceramic disks. By comparing permeate fluxes in different configurations, membranes on both shafts, membranes on the 1st shaft with and without metal disks on the 2nd shaft, we showed that, at a feed concentration of 200 g L⁻¹, the effect on permeate flux J, of shear rate increment due to membrane overlapping, could be completely offset by the high concentration increase between two adjacent and overlapping membranes. Raising the ceramic disks rotation speed N_c had a larger effect on J than increasing the metal disks speed N_m. For N_c = 32.16 Hz (1930 rpm) and N_m = 2.4 Hz (144 rpm), J reached 1790 L h⁻¹ m⁻² at 310 kPa, versus 1100 L h⁻¹ m⁻² for N_c = 12.3 Hz (738 rpm) and N_m = 22.26 Hz (1336 rpm) (for the same total sum N_c + N_m). Measurements of electrical power consumed by friction on rotating disks showed that the energy spent per m³ of permeate was lowest when using metal disk with vanes rotating at low speed and ceramic disks rotating at high speed.     

Influence of solvents on the formation of ultrathin uniform poly(vinyl pyrrolidone) nanofibers with electrospinning

Although there have been many reports on the preparation and applications of various polymer nanofibers with the electrospinning technique, the understanding of synthetic parameters in electrospinning remains limited. In this article, we investigate experimentally the influence of solvents on the morphology of the poly(vinyl pyrrolidone) (PVP) micro/nanofibers prepared by electrospinning PVP solution in different solvents, including ethanol, dichloromethane (MC) and N,N‐dimethylformamide (DMF). Using 4 wt % PVP solutions, the PVP fibers prepared from MC and DMF solvents had a shape like a bead‐on‐a‐string. In contrast, smooth PVP nanofibers were obtained with ethanol as a solvent although the size distribution of the fibers was somewhat broadened. In an effort to prepare PVP nanofibers with small diameters and narrow size distributions, we developed a strategy of using mixed solvents. The experimental results showed that when the ratio of DMF to ethanol was 50:50 (w/w), regular cylindrical PVP nanofibers with a diameter of 20 nm were successfully prepared. The formation of these thinnest nanofibers could be attributed to the combined effects of ethanol and DMF solvents that optimize the solution viscosity and charge density of the polymer jet. In addition, an interesting helical‐shaped fiber was obtained from 20 wt % PVP solution in a 50:50 (w/w) mixed ethanol/DMF solvent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3721–3726, 2004     

多尺度结构Ag/PA6纳米纤维膜的制备及其催化性能

随着工业的进步,废水处理特别是印染废水的处理成为亟待解决的问题.银纳米粒子因其特殊的物理化学性能而表现出催化活性,但银纳米粒子的团聚限制了其使用,所以出现了一系列新的载体材料,如微球、薄膜和纤维等.其中电纺纳米纤维由于具有高比表面积,作为载体材料具有非常大的优势,而将常规电纺纳米纤维作为载体也已有报道.但是,将具有更高比表面积的电纺纳米纤维作为载体,特别是一种类似于树枝状结构的多尺度纳米纤维作为载体还鲜有报道.本文制备了一种多尺度结构的PA6纳米纤维膜,该纳米纤维膜由直径为50?120 nm的主纤维和10?50 nm的分支纤维构成;由于分支纤维的出现,多尺度结构纳米纤维膜的比表面积得到了提高,可以为银纳米粒子的负载提供更多附着位点.制备的多尺度结构纳米纤维膜通过银胶溶液浸渍成功地负载银纳米粒子,对制备的纳米纤维膜的形态、化学结构以及对亚甲基蓝的催化性能进行了探讨.SEM,EDS和TEM结果表明,银纳米粒子成功地负载在多尺度结构纳米纤维的表面,并且银纳米粒子的粒径以及负载量可以通过变换银胶溶液的浓度合理调控.此外,与常规PA6纳米纤维膜相比,多尺度结构纳米纤维膜更有利于银纳米粒子的分散,同样通过银胶溶液A浸渍,负载在多尺度结构纳米纤维上银纳米粒子粒径为8.6 nm,而负载在普通PA6纳米纤维上银纳米粒子粒径为11.2 nm.XPS分析表明,银纳米粒子成功地负载到多尺度结构纳米纤维上,并且经不同银胶溶液处理,纳米纤维膜的载银量不同.通过O的高能XPS分析发现,银纳米粒子与PA6分子间形成了配位键,这在一定程度上有利于Ag纳米粒子的固定,阻止了Ag纳米粒子的团聚.Ag/PA6纳米纤维膜以及多尺度结构Ag/PA6纳米纤维膜催化降解实验表明,多尺度结构Ag/PA6纳米纤维膜具有较高的催化活性,反应2 h后对10 mg/L亚甲基蓝的降解率达到98.13%,并且降解过程符合伪一级动力学.不同浸渍液浓度处理纳米纤维膜催化实验表明,Ag纳米粒子的大小以及含量都会影响纳米纤维的催化活性,纳米粒子粒径越小,其催化活性越高;不同NaBH4加入量催化体系催化实验表明,随着NaBH4加入量的增大,催化体系的降解率增高,其对催化体系的催化性能起着至关重要的作用;其他条件一定,随着染料初始浓度的增大,催化体系的催化性能下降;循环实验表明,经5次循环之后,其降解率仍高达83.5%,该纳米纤维膜具有一定的循环使用性能.     

Phosphorus intercalation of halloysite nanotubes for enhanced fire properties of polyamide 6

The fire performance of polyamide 6 (PA6) blended with phenyl phosphonic acid functionalized halloysite nanotubes (PPA‐HNTs) is evaluated in order to determine if there is any fire performance gains over the unmodified composite. In the continuing search for safe halogen‐free fire retardants for polymers, and the desire to more fully capture the advantages of nano‐materials, this research seeks to utilize any synergy which might result in improved fire performance of PA6, via the known advantages offered by nano particles and phosphorus‐based compounds. HNTs offer the ability for functionalization by exchange at their hydroxyl sites, while PPA can readily attach at these sites because of its acidity. In this context, the nanotubes act as a carrier for the acid within the polyamide polymeric matrix because it is readily intercalated and functionalized with the acid. The intercalated nano particles are added to the polyamide via melt extrusion and then analyzed using thermal analysis and cone calorimetry. The key finding from this work is that functionalization of HNTs with PPA, followed by blending into PA6 results in a significant improvement in fire performance by altering the combustion dynamics of the polymer. This work proposes a new synergistic fire retardant system for polyamides utilising relatively safe and inexpensive components. More broadly, the concept of using a carrier such as HNTs, which is so easily functionalized, can be applied to other thermoplastic materials, and other additives, for improvements in material properties other than fire. Copyright © 2012 John Wiley & Sons, Ltd.     

The effect of electrophoretic deposition p-aminobenzenesulfonamide grafted CNT on mechanical properties of carbon fiber filled polyamide 6 composite

The surface treatment of carbon fiber is carried out by electrophoretic deposition of p-aminobenzenesulfonamide grafted carbon nanotube (CNT), and it is used as a reinforcement of polyamide 6. The monofilament tensile test and XPS were used to study the effect of p-aminobenzenesulfonamide concentration on the tensile strength and surface functional groups of carbon fiber monofilaments. The results show that the higher the p-aminobenzenesulfonamide concentration, the greater the decrease in the mechanical properties of carbon fibers, and the greater the content of oxygen-containing functional groups on the surface. It is preferred that carbon fiber and thermoplastic polyamide 6 with higher retention rate of monofilament tensile strength and rich oxygen-containing functional group content are made into composite materials, and the interlaminar shear strength (ILSS) is evaluated.     

Barrier property enhancement of polyamide 6 by blending with a polyhydroxyamino‐ether resin

In this work, the transport properties of the system formed by polyamide 6 (PA6) and polyhydroxyamino‐ether resin (PHAE) have been studied after characterizing the miscibility behavior. A single glass transition has been observed using differential scanning calorimetry that usually means total miscibility, but measurements by solid‐state cross‐polarization magic angle spinning NMR have shown that this system is only partially miscible, in good agreement with phase behavior reported before. Both carbon dioxide and water vapor transport properties of PA6/PHAE blends have been measured. For both penetrants, permeability coefficient shows an interesting negative deviation from the additive value, even the barrier character to carbon dioxide of pure PHAE is maintained up to 60 % in PA6 composition. Besides, PHAE reduces the plasticization effect of water in PA6. These improvements are very interesting for the PA 6 due to its wide use in packaging applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1625–1634, 2009     

Promotion of the γ‐phase of polyamide 6 in its nanocomposite with phosphate glass

The effect of tin fluorophosphate‐glass (Pglass) nanoparticles on the polyamide‐6 (PA6) matrix in Pglass/PA6 hybrids has been investigated by ¹³C solid‐state nuclear magnetic resonance (NMR). The crystallinity determined by direct‐polarization ¹³C NMR combined with longitudinal relaxation‐time (T_1C) filtering varied between 31 and 44%. T_1C‐filtered ¹³C spectra with cross polarization clearly showed resonances of both the α‐ and γ‐crystalline phases of PA6, typically at ratios near 45:55, while the similarly processed neat polymer contained only the α‐phase. This suggests that the Pglass promotes the growth of the γ‐crystalline phase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 857–860, 2008     

On the prediction of permeate flux for nanofiltration of concentrated aqueous solutions with thin-film composite polyamide membranes

The nanofiltration of binary aqueous solutions of glucose, sucrose and sodium sulfate was investigated using thin-film composite polyamide membranes with different molecular weight cut-off's. The NF experiments, in total recycle mode, were performed in a plate-and-frame module Lab 20 (AlfaLaval), at 22 °C and with a flowrate of 8.2 L/min, using the membranes NF90, NF200 and NF270 from FilmTec (Dow Chemical), for transmembrane pressures between 1 and 6 MPa and with aqueous solutions with osmotic pressures of between 0.5 and 3.0 MPa. The permeate flux was predicted by the osmotic pressure model, using the membrane hydraulic resistance and the solution viscosity inside the membrane pores, and computing the concentration polarization with recourse to a mass-transfer correlation specific for the plate-and-frame module used. The flux predictions, using the pure water viscosity, agree reasonably with the experimental data only for low transmembrane pressures and with the most diluted solutions. For higher transmembrane pressures and for higher solute concentration the predicted fluxes can be as far as 2.5, 4.1 and 9.6 times higher than the experimental one, for the aqueous solutions of Na₂SO₄, glucose and sucrose, respectively. These deviations are strongly reduced when the pure water viscosity is replaced by the solution viscosity adjacent to the membrane. In this case, the maximum deviation between predictions and experiments occurs also for higher transmembrane pressures and for higher solute concentration, but the maximum ratio between predicted values and the experiments were reduced now to 1.8, 2.1 and 2.9, for the aqueous solutions of Na₂SO₄, glucose and sucrose, respectively. Even using the solution viscosity adjacent to the membrane, and for the systems investigated, the osmotic pressure model must used with caution for design purposes because it may over predict the permeate flux by a factor of about 2 when the solute concentration is high.     

Simultaneously improving the flame retardancy and mechanical properties for polyamide 6/aluminum diethylphosphinate composites by incorporating of 1,3,5‐triglycidyl isocyanurate

The effect of 1,3,5‐triglycidyl isocyanurate (TGIC) as a synergistic agent on the fire retardancy, thermal, and mechanical properties for polyamide 6/aluminium diethylphosphinate (PA6/AlPi) composites were investigated in detail by limiting oxygen index; vertical burning (UL‐94); cone calorimeter; thermal gravimetric analysis; rheological measurements; and the tests of tensile, flexural, and Izod impact strength. The morphologies and chemical compositions of the char residue were investigated by scanning electron microscopy, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectra. The results demonstrated that AlPi and TGIC exerted an evident synergistic effect for flame retardant PA6 matrix, and the PA6/AlPi/TGIC composites with the thickness of 1.6 mm successfully passed UL‐94 V‐0 rating with the limiting oxygen index value of 30.8% when the total loading amount of AlPi/TGIC with the mass fraction of 97:3 was 11 wt%. However, the samples failed to pass the UL‐94 vertical burning tests when AlPi alone is used to flame retardant PA6 matrix with the same loading amount. The thermal gravimetric analysis data revealed that the introduction of TGIC promoted the char residue formation at high temperature. The rheological measurement demonstrated that the incorporation of TGIC improved the storage modulus, loss modulus, and complex viscosity of PA6/AlPi/TGIC composites comparing with that of neat PA6 and PA6/AlPi composites due to the coupling reaction between TGIC and the terminal groups of PA6 matrix. The morphological structures of char residues demonstrated that TGIC benefited to the formation of more homogenous and integrated char layer with no defects and holes on the surface comparing with that of PA6/AlPi composites during combustion. The higher melt viscosity of composites and the integrated and sealed char layer effectively inhibited the volatilization of flammable gas into the combustion zone and then led to the reduction of the heat release. The results of mechanical properties revealed that the incorporation of TGIC enhanced the mechanical properties for PA6/AlPi/TGIC composites comparing with that of PA6/AlPi composites with the same loading amount of flame retardant caused by the chain extension effect of TGIC. As a result, the flame retardancy and mechanical properties of PA6/AlPi composites simultaneously enhanced due to the introduction of TGIC.     

Effect of surface chemical modification for aluminum hypophosphite with hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene on the fire retardancy,water resistance,and thermal properties for polyamide 6

The surface chemical modified aluminum hypophosphite (AHP) defined as MAHP was successful prepared through P–H bonds on AHP surface reacted with the aldehyde groups in hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene made in our lab. The wettability of the flame retardants was evaluated by water contact angle tests, and the water contact angle of the prepared MAHP dramatically increased from 0° for AHP to 145°, which indicated the surface modification made the superhydrophilic AHP into superior hydrophobic MAHP. The prepared MAHP and AHP, respectively, incorporated into polyamide 6 (PA6) matrix to prepare flame retardant PA6 composites and the fire retardancy and thermal degradation behavior of flame retardant PA6 composites were investigated by limiting oxygen index, vertical burning test (UL‐94), cone calorimeter, and thermogravimetric analysis tests. The morphologies and chemical compositions of the char residues for PA6 composites were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. The water resistant properties of flame retardant PA6 composites were evaluated by putting the samples into distilled water at 70°C for 168 hr, and the mechanical properties for flame retardant PA6 composites were investigated by the tensile, flexural, and Izod impact strength tests. The results demonstrated that the PA6/MAHP composites successfully passed UL‐94 V‐0 flammability rating, and the limiting oxygen index value was 27.6% when the loading amount of MAHP was 21 wt%. However, there is no rating in vertical burning tests for PA6/AHP composite with the same amount of AHP, which indicated the surface modification of AHP enhanced the flame retardancy efficiency for PA6 composites. The morphological structures and analysis of X‐ray photoelectron spectroscopy of char residues revealed that the surface modification of AHP benefited to the formation of a sufficient, flame retardant elements rich, more compact and homogeneous char layer on the materials surface during combustion, which prevented the heat transmission and diffusion, limit the production of combustible gases, inhibit the emission of smoke and then led to the reduction of the heat release rate and smoke produce rate. The mechanical properties results revealed that the surface modification of AHP enhanced the mechanical properties, especially the Izod impact strength comparing with that of PA6/AHP composites with the same amount of flame retardant. After water resistance tests, the PA6/MAHP composites remained superior flame retardancy and presented continuous and compact char layer after cone calorimeter tests; however, the fire retardancy for PA6/AHP composite obviously decreased, and the char layer was discontinuous with big hole caused by the extraction of AHP by water during water resistance tests. Copyright © 2017 John Wiley & Sons, Ltd.     

The fabrication of hollow fiber membranes with double-layer mixed-matrix materials for gas separation

The concept of fabricating hollow fibers with double-layer mixed-matrix materials using the same polymeric matrix has been demonstrated for gas separation. Polyethersulfone (PES)–beta zeolite/PES–Al₂O₃ dual-layer mixed-matrix hollow fiber membranes with enhanced separation performance have been fabricated. This study presents an innovative approach of utilizing low cost PES and Al₂O₃ to replace expensive polyimides as the supporting medium for dual-layer mixed-matrix hollow fibers and eliminating interlayer de-lamination problems. The incorporations of 20 wt% beta zeolite in the outer selective layer and 60 wt% Al₂O₃ in the inner layer coupled with spinning at high elongational draw ratios yield membranes with an O₂/N₂ selectivity of 6.89. The presence of Al₂O₃ particles enables the membrane to retain its porous substructure morphology in the course of annealing above the glass transition temperature of PES. Moreover, spinning at high elongational draw ratios results in the re-distribution of Al₂O₃ particles towards both edges of the inner layer. Not only do the permeance and selectivity of the fibers increase, but also greater mechanical properties and lower degree of shrinkages are obtained. Therefore, the combination of PES–beta zeolite and PES–Al₂O₃ nanoparticles with a reasonable draw ratio may be another promising approach to produce hollow fibers with double-layer mixed-matrix materials.     

The study of oxidization fluorescence sensor with molecular imprinting polymer and its application for 6-mercaptopurine (6-MP) determination

This paper developed optical fiber sensor based on molecular imprinted polymer as artificial recognition element for the determination of 6-mercaptopurine (6-MP) in human serum. This approach displayed high sensitivity by oxidizing 6-MP to a strong fluorescent compound with H₂O₂ in the alkaline media. It offered a relatively nice selectivity for 6-MP detection by molecular imprinted polymer's recognition. The relative standard deviation (R.S.D.) was 5% for a same sensor (n = 5) when 6-MP concentration was 1.0 × 10⁻⁷ g mL⁻¹ in serum. The developed method was satisfactorily applied to the determination of 6-MP in human serum without any necessity for sample treatment or time-consuming extraction steps prior to the analysis.     

吖啶橙-罗丹明6G能量转移荧光法测定痕量磷

在λex/λem=450/556nm,十二烷基苯磺酸钠(DBS)存在下,吖啶橙-罗丹明6G能够能有效能量转移,使罗丹明6G荧光大大增强,酸性条件下,正酸根与钼酸钼反应生成磷钼酸,磷钼酸与R6G形成离子缔合物,使R6G的光猝来利用吖淀橙-罗丹明6G能量转变荧光法测定痕量磷,提高了测定磷的灵敏度和选择性,磷含量的0.05~0.70μg/L 范围内与罗丹明6G的荧光猝程度呈良好的线性关系.最低检出限为5ng/L,回收率为95%~110%,测定0.50μg/L,磷溶液,相对标偏差为6%,该法用于水样及土壤中的活性磷的测量,结果满意.     

Copolymerization of norbornene with methoxycarbonylnorbornene catalyzed by Ni{CF3C(O)CHC[N(naphthyl)]CH3}2/B(C6F5)3 catalytic system and good processability for Dry/Wet phase inversion and electrospinning technique

Copolymerization of norbornene (NB) with methoxycarbonylnorbornene (NB‐COOCH₃) was carried out with catalytic system of Ni{CF₃C(O)CHC[N(naphthyl)]CH₃}₂ and B(C₆F₅)₃ in toluene. The catalytic system exhibited higher activity 2.69 × 10⁵ (gpolymer/mol Ni h) for copolymerization of norbornene and methoxycarbonylnorbornene. The influence results of the comonomer feed content on the polymerization showed that the NB‐COOCH₃ has a very high insertion ratio in all copolymers, and the NB‐COOCH₃ content in copolymers can be controlled to be 7.9–77.6 mol % at content of 10–90 mol % of the NB‐COOCH₃ in the monomer feeds ratios. The reactivity ratios, r_NB‐COOCH3 = 0.578 and r_NB = 0.859, were determined by the Kelen–TÜdÕs method. Copolymers were processed by solution casting method, dry/wet phase inversion technique, and electrospinning. The films prepared by solution casting method showed good transparency in the visible region. The membranes processed by dry/wet phase inversion technique were microporous structures. The fibers diameters fabricated by electrospinning were about 3 μm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Solvent effects on extraction of potassium picrate with benzo-18-crown-6. A new equation for the determination of ion-pair formation of crown ether-metal salt complexes in water

In order to determine the ion-pair formation constant of a crown ether-metal salt 1:1:1 complex in water, an equation is derived from regular solution theory and its predictions are verified experimentally by the solvent extraction method using benzo-18-crown-6 (B18C6), potassium picrate (KA), and various diluents of low dielectric constant. The distribution constants of B18C6 itself and the overall extraction constants of KA with B18C6 were determined at 25±0.2°C. The distribution constants of the neutral K(B18C6)A complex were calculated from these data. The literature value for the complex-formation constant of K(B18C6)⁺ in water and the ion-pair formation constant (K _K(B18C6)A ) for K(B18C6)A in water determined in this study were log K _K(B18C6)A =3.12±0.23 at 25°C). The distribution behavior of B18C6 and K(B18C6)A is explained in terms of regular solution theory. The molar volumes V (cm³·mol^–1) and solubility parameters (cal^1/2-cm^–3/2) are as follows: V _B18C6 =249±36; V _K(B18C6)A =407±56; _B18C6 = 11.5 ± 0.5; and _K(B18C6)A = 11.5 ± 0.5.