A method of production of hemosorbent based on thermally expanded graphite is developed. The method involves the electropolymerization of pyrrole on rolled thermally expanded graphite and subsequent cyclic electrochemical doping of polypyrrole film with Cl? anions. The method enables one to produce a hemosorbent with an open-circuit potential, which is necessary for its biocompatibility. 相似文献
An effective process for the synthesis of graphite nanosheets/AgCl/polypyrrole (NanoGs/AgCl/PPy) composites was developed. NanoGs were prepared by treating the expanded graphite with sonication in aqueous alcohol solution. Then nanocomposites were fabricated via in situ polymerization of pyrrole in the presence of NanoGs and AgCl particles through two-step sequentially inverse microemulsion method. The nanoscale dispersion of NanoGs and AgCl particles was evidenced by the SEM and TEM examinations. From the thermogravimetric analysis, the introduction of inorganic nano-AgCl and NanoGs exhibited a beneficial effect on the thermal stability of pure PPy. According to the four-point-probe test, the conductivity of the final NanoGs/AgCl/PPy composites was dramatically increased compared with pure PPy. 相似文献
In this study graphite electrodes modified by a thin DNA‐imprinted polypyrrole layer, which was able to bind specific target‐DNA, are reported. For this aim, electrochemical synthesis of polypyrrole was performed on a pencil graphite electrode by cyclic voltammetry (CV) or by potential pulse sequences (PPS). The modified electrode surface was used for electrochemical determination of target‐DNA by differential pulse voltammetry. According to our best knowledge this is a first report on the application of DNA‐imprinted polymer for the determination of target‐DNA. The results showed that the molecularly imprinted polypyrrole (MIPPy) layer that formed on the carbon electrode surface was sensitive for target‐DNA, while the nonimprinted polypyrrole layer was not sensitive to the same target‐DNA. Comparison of electrodes modified using PPS and CV techniques is presented. 相似文献
This paper reports the development and characterization of a solid state potentiometric sensor for chloride ions, based on doped polypyrrole‐graphite‐epoxy composite. The optimum mixture proportion found for polypyrrole:graphite was 60 : 40 meanwhile a 50 : 50 proportion was used for the polypyrrol+graphite:epoxy mixture. The stabilization time was approximately 16 min, while the response times varied within 2 and 23 s. The sensor displayed a sensitivity of 58 mV/decade [Cl?], and 3×10?6 M detection limit. The selectivity coefficients showed a greater selectivity to that reported for commercial‐type sensors. The statistical analysis for chlorides' determination in commercial saline serums did not show significant differences respect to data reported by the manufacturers. 相似文献
Summary: Polypyrrole is one of the most widely‐studied conducting polymers due to its steady electrochemical response and good chemical stability in different solvents, including organic and inorganic ones. In this work, we provide for the first time valuable information in atomic detail concerning the steady and dynamic properties of pyrrole rings as a function of the oxidation state of the polymer. The study was carried out by Classical molecular dynamics simulation, where the system was modelled by 256 polypyrrole chains of 10 pyrrole rings each. Water was explicitly introduced in our simulations. Besides the uncharged or reduced state, two steady oxidation states of the polymer have been simulated by introducing a net charge (+1) on 85 and 256 of the polypyrrole chains. To balance the charges emerging in these oxidised states, 85 and 256 chloride ions (Cl−1) respectively, were introduced into the system. From an analysis of the simulated trajectories, the orientation and relaxation times of water and pyrrole rings were evaluated for the different oxidation states of the polymer across the polypyrrole/water interface. The calculated densities for different oxidation states describe the swelling or shrinking process during electrochemical oxidation or reduction respectively. The rotational relaxation times calculated for the polypyrrole rings decrease with increasing oxidation of the polymer, which is in a good agreement with experimental electrochemical data. Almost no variation in pyrrole ring orientation was measured for the different oxidation states of the polymer, even compared with polypyrrole bulk. As regards the water structure in the vicinity of the polypyrrole/water interface, both the orientation and orientation relaxation time were strongly affected by the presence of charges in the polymer. Thus, the water dipole was strongly orientated in the vicinity of the water/polypyrrole interface and its orientational relaxation time increased by one order of magnitude compared with bulk water, even when only one‐third of the total polymer chains were oxidised. The results attained in this work were validated with experimental results, when they were available.
Polypyrrole ring orientation and water orientation at the polypyrrole/water interface. (a) 256 rPPy and (b)171 rPPy + 85 oPPy. 相似文献
Expanded graphite was prepared by the intercalation of natural graphite using ammonium peroxodisulfate as an oxidizing agent and a high purity of sulfuric acid as an intercalate. The amounts of oxidizing agent and intercalate were changed to determine the preparation conditions of expanded graphite as the anode material for high-power Li-ion batteries. The expanded graphite was tested as the anode material and further composited with the different amounts of petroleum pitch to improve the electrochemical properties. Although the expanded graphite anode showed the improved electrochemical properties such as initial reversible capacities of around 400 mAh/g and a charge capacity at 5 C-rate of 83 mAh/g as compared with those for the natural graphite anode of 378 and 19.4 mAh/g, respectively, it still had some weak points for a high-power anode material such as low initial efficiency and potential plateaus with the stage characteristic. The anode composites with high performance could be obtained by compositing the expanded graphite and the petroleum pitch at the ratio of 1:2, showing an improved initial efficiency of 78 % and decreased potential plateaus with 389 mAh/g of the initial reversible capacity. 相似文献
A renewable potentiometric immunosensor for detection of immunoglobulin G (IgG) has been developed by magnetic force attraction of Fe3O4 nanoparticles immobilized goat‐anti‐human IgG antibody. For preparing sensitive film of the sensor, cysteine was bonded on the nano‐Fe3O4 particles surface. The cysteine functionalized magnetic nanoparticles was attracted on a solid paraffin carbon paste electrode surface to covalently immobilize of anti‐immunoglobulin G (anti‐IgG) by employing a conventional glutaraldehyde‐crosslinking method. The immunosensor showed a specific response to human immunoglobulin G in the range of 0.1–1.2 ng/mL with a detection limit of 0.023 ng/mL. The immunosensor based on the magnetic nanoparticles was made easily by this method. It can be used expediently, renewed easily and low‐cost relatively. The renewable potentiometric immunosensor with better stability and higher sensitivity can be employed extensively in clinical diagnosis, monitoring of disease and environmental studies and etc. 相似文献