Metal atoms, incorporation into polymers

Metal atoms can be incorporated into polymers using two approaches. For probing new reactions between metal atoms and polymers a small-scale spectroscopic approach, sometimes referred to as the Fluid Matrix Technique (11), is used. The coreactant polymer matrix, containing on the order of 0.5 fll of polymer, is preformed on an optical surface. In the case of viscous fluids such as 2 the material is painted on the substrate and held at temperatures ranging typically from 200 to 270 K. The temperature is chosen to maintain low volatility but retain mobility. Under high vacuum [10 6 torr]... 

Metal-containing polymers may be produced by various methods, such as chemical reactions of precursors— in particular, reactions of metal salts in polymer solutions, the treatment of polymers with metal vapors, or the polymerization of various metal-monomer systems [1-4], Depending on the metal nature and the polymer structure, these processes lead to organometallic units incorporated into polymer chains, metal-polymer complexes, or metal clusters and nanoparticles physically connected with polymer matrix. Of special interest are syntheses with the use of metal vapors. In this case, metal atoms or clusters are not protected by complexones or solvate envelopes and consequently have specific high reactivity. It should be noted that the apparatus and principles of metal vapor synthesis techniques are closely related to many industrial processes with participation of atomic and molecular species [5]—for example, manufacturing devices for microelectronic from different metals and metal containing precursors [6]. Vapor synthesis methods employ varying metals and... 

The topic of metal- and metalloid-containing polymers can be divided by many means. Here, the topic will be divided according to the type of reaction employed to incorporate the inorganic atom into the polymer chain. While many other types of reactions have been employed to produce metal- and metalloid-containing polymers including redox, coupling,... 

The Fischer-Hafner synthesis of sandwich compounds (33) does not permit functional groups to be incorporated into the arenes because of side reactions with the Lewis acid catalyst (Friedel-Crafts reducing conditions). This is not the case when metal atoms are used directly. Many metal-arene complexes have been identified that contain F, Cl, CH30, R2N and C02R substituents. It is reasonable to assume that polymer-bound phenyl substituents containing these functional groups will yield similar sandwich complexes. 

Due to this chain-migration process ethylene is polymerized to macromolecules containing multiple branches - rather than to the linearly enchained polymer obtained with classical solid-state catalysts. In propylene polymerization with these catalysts 1,2-insertions give the normal methyl-substituted polymer chains, but after each 2,1-insertion the metal centre is blocked by the bulky secondary alkyl unit and can apparently not insert a further propylene. Instead the metal must then first migrate to the terminal, primary C atom before chain growth can continue by further propylene insertions. By this process, also called 1,CO-enchainment or polymer straightening, some of the methyl or (in the case of higher olefins) alkyl substituents are incorporated into the chain. 

Organic polymers are also generally believed to manifest ferromagnetism only when impurities (especially transition metals) are present, or when transition metals are deliberately incorporated into them. There is, however, some evidence [10] of ferromagnetism in organic polymers containing some specialized types of structural and electronic features but not containing appreciable amounts of transition metal atoms. 

---