A wholly-aromatic thermotropic liquid crystalline polymer (WATLCP) composed ofp-hydroxybenzoic acid (HBA), 4,4'-dihydroxy bisphenyl (BP), terephthalic acid (TPA),m-phthalic acid (MPA) was synthesized. It was symbolized by BP-LCP. Using a simi-lar method, a new copolymer BP-PSF was prepared. BP-PSF has a semi-flexible chainpolysulfone and a rigid-rod chain like BP-LCP. By FT-IR, polarizing microscope and DSCtechnique, the structures and properties of BP-LCP and BP-PSF were studied. 相似文献
We report on a new enzyme/support system to immobilize proteins such as enzymes through a covalent bond on polysulfone membranes. In the present case the enzyme endo-1,4-β-xylanase (E.C.3.2.1.8) is attached to polysulfone previously derivatized by introducing an acrylate group. Membranes are properly prepared from this polysulfone acrylate. Afterwards the enzyme is immobilized though the amino groups of side chains of the amino acids of the enzyme and the acrylate group of the derivatized polysulfone. Such immobilization of the enzyme is confirmed by microelemental analysis as well as by amino acid analysis by HPLC. Moreover, the enzymatic activity of the membranes was evaluated and compared with that corresponding to the free enzyme. Certain physical parameters (asymmetry, irregularity, pore size and surface roughness) of the corresponding enzymatic membranes were obtained from SEM and AFM image interpretation. 相似文献
Asymmetric polysulfone membranes were prepared by wet phase inversion method with different demixing rate of casting solutions. The influent factor of demixing rate was focused on the polarity of additive in the polysulfone/N-methyl-2-pyrrolidone/water ternary system. With increasing the polarity of alcohols in the casting solution, the decrease in skin layer thickness was observed and then a poor separation performance of membranes can be obtained. It was found that the polar additive caused the rapidly demixing of casting solution in coagulation bath and formed porous asymmetric membranes with defective skin layer. In the other case, chloroform was used as the non-polar additive in casting solution. With increasing the mount of chloroform in the casting solution, the increase in skin layer thickness was observed and then lead to a good separation performance of these membranes. It was found that of the non-polar additive delays the demixing rate of casting solution in this ternary system. The separation performance of these asymmetric membranes were characterized by the measurement of dehydration of ethanol/water mixture by pervaporation and observed the morphology by scanning electron microscopy. It was found that the separation performance of asymmetric polysulfone membrane strongly depends on the polarity of adding solvent in polysulfone/N-methyl-2-pyrrolidone/water ternary system. 相似文献
This work presents a comparative study between two different methods for the preparation of mediator-modified screen-printed electrodes, to be used as detectors in a reliable flow injection system for the determination of the nicotinamide adenine dinucleotide (NADH) coenzyme. The best strategy was selected for the final development of compact biosensors based on dehydrogenase enzymes. For the first immobilisation strategy, different redox mediators were electropolymerised onto the SPE surface. The second immobilisation strategy was carried out using polysulfone–graphite composites, which were deposited by screen-printing technology onto the screen-printed electrode (SPE) surface. Both methods achieved an effective and reliable incorporation of redox mediators to the SPE configuration. Finally, a flow system for ammonium determination was developed using a glutamate dehydrogenase (GlDH)-Meldola's Blue (MB)-polysulfone-composite film-based biosensor.
The stability of the redox mediators inside the composite films as well as the negligible fouling effect observed on the electrode surface improve the repeatability and reproducibility of the sensors, important features for continuous analysis in flow systems. Furthermore, the optimised bio/sensors, incorporated in a flow injection system, showed good sensitivities and short response times. Such a good analytical performance together with the simple and fast sensor construction are interesting characteristics to consider the polysulfone-composite films as attractive electrochemical transducer materials for the development of new dehydrogenase-based SPEs. 相似文献
trans-Stilbene, 1, 1-diphenylethylene, and α-methylstyrene were allowed to react with dibenzylmagnesium to form their oligomers in hexamethylphosphortriamide (HMPA). One and two molecules of stilbene and 1, 1-diphenylethylene were incorporated into the magnesium carbon bond, and the carbanions obtained in HMPA were stable in analogy with the anionic living polymer having alkali cation as the gegenion in eithers. Intense coloration was observed during the reaction between α-methylstyrene and dibenzylmagnesium as well as in the case of stilbene and 1, 1-diphenylethylene. The low molecular weight products which were formed after a long time in the reaction between α-methylstyrene and dibenzylmagnesium were found to have no magnesium-carbon bond. It was considered that the cleavage of the propagating chain occurred gradually after the rapid propagation had proceeded to consume the monomer. 相似文献
The anion-exchange membrane was prepared by a two-step synthesis: chloromethylation of the homemade block copolymers of polysulfone (PSf) and polyphenylenesulfidesulfone (PPSS) in the first step with subsequent amination by means of trimethylamine in the second step. The lowest measured area resistivities, equilibrated in 2 mol/dm3 KCl aqueous solution, were 4.5–3.30 Ω cm2. The anion-exchange capacity reached up to 0.92 meq/(g-dry-resin), and the transport number of chlorine anion was in the 0.6–0.7 range. 相似文献
The optimum performance of an optical oxygen sensor based on polysulfone (PSF)/[Ru(II)-Tris(4,7-diphenyl-1,10-phenanthroline)] octylsulfonate (Ru(dpp)OS) was checked by carefully tuning the parameters affecting the membrane preparation. In particular, membranes having thickness ranging between 0.2 and 8.0 μm with various luminophore concentrations were prepared by dip-coating and tested. The membrane thickness was controlled by tuning the solution viscosity, and was measured both by secondary ion mass spectrometry (SIMS) and by visible spectroscopy (Vis). Luminescence-quenching-based calibration was a single value of the Stern-Volmer constant (K′SV) for membranes containing up to 20 mmol Ru(dpp) g−1 PSF (1.35 μm average thickness). The K′SV value decreased for larger concentration. The highest sensitivity was obtained with membrane thickness around 1.6 μm, having a response time close to 1 s. Thicker membranes exhibited an emission saturation effect and were characterized by longer response time. The K′SV behavior was interpreted on the basis of a mathematical approach accounting for the contribution of luminescence lifetime (τ0), oxygen diffusion coefficient (DO2) and oxygen solubility inside the membrane (sO2) establishing the role of all of them and allowing their experimental determination. Moreover, a simple experimental way to estimate K′SV without needing calibration was proposed. It was based either on the light emission asymmetry or on the percent variation of light emission on passing from pure nitrogen to pure oxygen. 相似文献
Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Differ... 相似文献