Polymer backbone metal-oxygen

A large variety of aluminum and silicon polymers with metal oxygen backbones have been made besides the poly(siloxanes). Poly(aluminosiloxanes) contain an Si-O-Al-0 backbone. A typical example results from the reaction of sodium salts of dimethylsiloxane oligomers with aluminum chloride. Polymers with Si/Al ratios of 0.8 to 23 have been made. Low Si/Al ratios are brittle and insoluble having a 3-dimensional structure while those with Si/Al ratios of 7 to 23 are soluble. 

In the early 1970s, Carraher and coworkers developed a number of different organometallic polymers containing metal-oxygen, metal-sulfur, and metal-nitrogen bonds in the polymer backbone. For example, a number of polyethers, " thioethers, amines, " esters, and oximes of titanium, zirconium, and hafnium were prepared. Scheme 1 shows the synthesis of haftiium, zirconium, and... 

Degradation of polyolefins such as polyethylene, polypropylene, polybutylene, and polybutadiene promoted by metals and other oxidants occurs via an oxidation and a photo-oxidative mechanism, the two being difficult to separate in environmental degradation. The general mechanism common to all these reactions is that shown in equation 9. The reactant radical may be produced by any suitable mechanism from the interaction of air or oxygen with polyolefins (42) to form peroxides, which are subsequentiy decomposed by ultraviolet radiation. These reaction intermediates abstract more hydrogen atoms from the polymer backbone, which is ultimately converted into a polymer with ketone functionahties and degraded by the Norrish mechanisms (eq. 

Polymer networks give low and uniform density distributions formed by crosslinking polymers. The polymers used contain the metal desired in the final ceramic. In some cases, the polymer backbone is a series of metal oxygen bonds making an inorganic polymer. 

In addition, oxygen diffusion to the metal/polymer interface was crucial and that the chemical portion of the bond did not result from oxygen within the polymer backbone itself. If it did, then samples heat treated in argon would display similar adhesion values to those processed in air. 

If oxygen is present the loose electrons are consumed for its reduction which may result in formation of oxygen radical anions and in the oxidative degradation of the polymer backbone. An irreversible degradation of conductivity of freshly prepared PPy exposed to oxygen has been reported [7]. On the other hand the relaxation of the EPs can be turned to advantage. If a metal salt is allowed to diffuse into a freshly prepared EP layer the subsequent spontaneous relaxation and reduction yields metal clusters that are finely dispersed throughout the polymer s bulk [8]. These... 

In the early 70s it was announced that organotin compounds had been bonded to such plastics as polystyrene, polymethacrylate, polyester, polyvinyl chloride, and cellulose polymer backbones. " These have been termed organometallic polymers (OMP). Triethyltin hydroxide was allowed to react with a copolymer of styrene-maleic anhydride. These polymers can be incorporated in a marine paint which, when applied, would retain an anti-fouling activity through hydrolytic cleavage of the metal-oxygen-polymer bond. 

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