Platinum condensation polymers

This method of preparation is suitable for producing primary alkyl lactates but is unsatisfactory for /3-methallyl lactate because the strong mineral acid catalyzes the rearrangement of methallyl alcohol to isobutyraldehyde. Methyl lactate can be made conveniently (80-85% yield) by heating 1 mole of lactic acid condensation polymer with 2.5-5 moles of methanol and a small quantity of sulfuric acid at 100 for 1-4 hours in a heavy-walled bottle, such as is used for catalytic hydrogenation with a platinum catalyst. 

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

Synthesis of Polymers. Polyamic acid solutions were prepared by condensation of the aromatic anhydride and amine in N,N-dimethylacetamide (DMAc). Polyimide modified electrodes were made by casting or spin coating the precursor polyamic acid solution onto stainless steel or platinum substrates. Imidization was achieved by either heating the films to 400°C for 60 min or through a chemical dehydration process involving immersion in a 1 1 mixture of acetic anhydride and pyridine (6). BTDA-DAPI films were made by casting from a DMAc solution and heating to 100 C. 

The polymer whose backbone is composed of platinum and alternately arranged butadiynyl and phenylenediethynylene groups, Pt-D1-Pt-D2 has been prepared by condensation of binuclear complex (38 a) with p-diethynylbenzene according to Eq. 22. Similarly, polymers, Pt-D -Pt-D1-Pt-D2 and Pt-D -Pt-D3, have been synthesized as described in Eqs. 23 and 2442). 

Monochloroanilines are made by reduction of chloronitrobenzenes with either iron/acid or, nowadays, mainly catalytic hydrogenation. Catalysts include platinum, copper chromite and rhenium in conjunction with palladium38. The chloroanilines are used in the manufacture of colorants, agricultural products, pharmaceuticals and polymers. For example, o-chloronitrobenzene (29) is a source of o-nitroanilinc, o-phenylenediamine (1,2-benzenediamine) (30), o-aminophenol (19b), o-chloroaniline and 3,3 -dichlorobenzidine (31a). The o-phenylenediamine (30) is a particularly versatile intermediate, used to prepare thioureidoformates. Ring-substituted o-phenylenediamines with cyanoesters yield benzimidazoles that, on condensation with an aldehyde, followed by treatment with H2S, give a range of thioureas. 

One of the more common two-part cure chemistries is based on the addition reaction of Si—H cross-links with vinyl functional polymers using platinum catalysts. This chemistry is shown below. One advantage of this addition chemistry is that it produces no cure by-products. Another common two-part chemistry involves condensation cure with alkoxysilane cross-linkers using Sn(IV) catalysts. 

The terminal -C=C-C=C-H containing platinum monomer can be condensed with fran5-Pt(PnBu3)Cl2 to afford the linear rod-like polymer where the platinum metal alternates with the butadiyne unit. The presence of the... 

The condensation of vapors of palladium, platinum, copper, or nickel into methycyclohexane solutions of o-butylaluminoxane, (uo-BuA10) in a rotating reactor was used to prepare small (<2 nm) colloidal metal partides. [133] These sols were notable in that stabilization of the metal partides was achieved in a nonpolar hydrocarbon with only Lewis add spedes stabilizers, instead of the usud polar donor polymers such as PVP, etc. [142] Tri-iso-butylaluminum itself was also effective in stabilizing the colloidal metals and gave pdladium particles with diameters less than 1.0 nm. [113]... 

Poly(carbazole) [20]. Solution of carbazole in acetonitrile may be electrochemically oxidized (counterion CIO4 or BF4) at a platinum anode to give electrically conductive films with poor mechanical stability. The polymers obtained by chemical coupling are mores stable. Poly(carbazole) has also been obtained by vacuum evaporation of carbazole and by chemical condensation. Doping with I2 or NOBF4 leads to conductivities an high as 1 S/cm. 

Block polymers containing polydimethylsiloxane soft blocks have been the subject of considerable recent synthetic activity. In particular, polydimethylsiloxane-b-polystyrene polymers have received considerable attention as thermoplastic elastomers. For the most part, anionic polymerization methods have provided the most successful routes to the preparation of these block polymers. Among the most notable papers in this field are those of Dean, Saam et al, Juliano, and Bajaj and coworkers. Recently Chaumont and his coworkers have prepared polydimethylsiloxane-b-polystyrene polymers by the platinum catalyzed condensation polymerization of a,o)-vinyl terminated polystyrene oligomers with a,o)-hydrogen terminated polydimethyl-siloxanes. 

Clearly it is essential that the sample, any volatile species, and any reactive atmosphere not react with the sample holder or other components with which they may come in contact. This is seldom an issue with polymers however, the interaction of phosphorous containing polymers with platinum above 900 °C is one exception. Condensation of volatile products on the suspension in cooler portions of the furnace may be avoided by using a sufficient gas flow or longer hot zone. The flow pattern of the atmosphere, the baffling, and the thermobalance configuration all affect the likelihood of such a problem. 

Between the pulses the gate is disconnected from the potentiostat, (open-circuit phase) and the potential of the platinum gate is dictated by the redox-state of the polymer The potential is approaching its equilibrium value, while the electrons spread from the electrode to equilibrate throughout the polymer film The redox polymer attached to the platinum surface functions as a condenser... 

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