Platinum polyacrylamide

Colloidal platinum dispersions, prepated by photoreduction of tetrachloroplatina-te(II) ion in the presence of a copolymer of IV-vinyl-2-pyrrolidone and acrylamide, are treated with polyacrylamide gel having amino groups, resulting in stable immobilization of colloidal particles onto the gel. The immobilized catalysts exhibit high activities for the hydrogenation of olefins at 30 °C and 1 atm 87). 

Fig. 2. Native polyacrylamide gel demonstrating the specific binding ofHMGl to a radio-labeled, platinated 123-bp DNA fragment. The DNA was modified with platinum compounds...

The polyacrylamide gel described abobe is the first example showing a reversible deformation of more than 100%. The effect is purely photochemical and reversible. However, this gel has a serious disadvatage in that the response time is slow. To improve this point the effect of electric field on the gel deformation was examined [44]. A rod-shaped polyacrylamide gel containing triphenylmethane leucocyanide groups (25 mm in length and 2 mm in section diameter) was prepared in a capillary tube. The gel rod was inserted between two parallel platinum electrodes in a small... 

Fig. 7,8. Reversible mercury-calomel electrode with the parts consisting of a 250 ml wide-mouthed reagent bottle, a vented and drilled rubber stopper, a soft glass tube with platinum wire sealed into the end, mercury, a wire to the output of the power supply, saturated KCl, and a glass tube containing 5% polyacrylamide gel made up in 1 M KCl. The tube dips into the buffer reservoir of the electrophoresis apparatus. The anode and cathode should be interchanged after each run. This arrangement will prevent all contamination of the buffer with electrode products even in very long runs (J. C. Finder, Ph.D. Thesis, London University, 1974).

GDH immobilized in polyacrylamide gel on the surface of a platinum net has been used by Chen and Liu (1977) for potentiometric glucose determination. At the optimal NAD+ concentration of 0.015 mmol/1 and 25° C the sensitivity was 15 mV/decade between 0.1 and 5 mmol/1 glucose. Addition of ferricyanide did not change these values, i.e., this substance was not active as an electron mediator. 

Glucose oxidase is immobilized in a polyacrylamide matrix. Oxygen and quinone which serve as mediators are reduced to hydrogen peroxide and hydroquinone, respectively. Since their oxidation starts at E, > 0.7-0.9 V, it is possible to displace the initial potential for the oxidation of glucose by 0.6-0.8 V towards positive values compared to its stationary electrochemical oxidation to gluconic acid on platinum. ... 

Entrapment in polyacrylamide gel over a platinum grid matrix Reaction with agarose cyclic imido-carbonate... 

Entrapment in polyacrylamide gel over a platinum grid matrix Glutaraldehyde-mediated reaction with a nylon-polyethyleneimine copolymer Reaction with macroporous aminated silo chrome coated with an acrolein-vinylpyridine copolymer Adsorption onto tannin coupled to amino hex y 1-cellulo se Entrapment in cellulose fibres Carbodi-imide-mediated reaction with chitosan... 

Garcia et al. [98] conducted coulometric initiation of acrylamide polymerization in oil-continuous AOT-toluene-water microemulsions using platinum/Nafion solid polymer electrodes (SPEs). The SPE served to separate the microemulsion from an aqueous electrolyte phase. Polymerization was initiated at room temperature by constant-potential electrolytic reduction of potassium persulfate initiator solubilized in the microemulsion droplets. Acrylamide monomer behaved as a cosurfactant and was required for the redox process. Latex particles and solid polyacrylamide were obtained. The kinetics of electroinitiated polymerization was slower than observed with UV or thermal initiation. Latex stability results suggest that coalescence is the primary mechanism for particle growth. 

Limoni and Schmuckler [ref. 37, 38] demonstrated that the anionic complexes of transition metal ions interact strongly with polyacrylamide gels. Based on the kinetic data obtained from breakthrough curves of chioro-complexes of copper, palladium and platinum on Bio-Gel P-2, the rate-determining step in the chromatographic process was found to be the detachment of solute molecules from the functional groups of the gel. 

Carboxylic acids have been prepared from carbonylation of aUyl bromide over palladium catalysts supported by polyphenol, polyvinylpyrrolidone,polyacrylamide (PAA), modified poly(2,6-dimethyl-l,4-phenylene oxide), and polysulfone- It is unclear under these reducing conditions if gel form metal cluster is involved as the active catalyst. Palladium acetate immobilized on the clay montmoriUonite has proved to be an effective catalyst for the carbonylation of secondary aUylic alcohols, affording a,/3-unsaturated carboxylic acids in moderate yields. However, triphenylphosphine was needed for the acliviva-tion of the catalyst. Palladium catalyst bound to a platinum cluster has been used up to three times for allylic alkylation without a significant loss of its activity. Preliminary study indicated that the Pd—Pt bond remains intact during the catalytic cycle. 

Entrapment in polyacrylamide gel mounted on to a rolled platinum electrode... 

Entrapment in polyacrylamide gel on platinum or on glutaraldehyde cross-linked on platinum... 

---