Metallic compounds in polymers

An original method of metallopolymer production by precursors thermal decomposition is to localize the particles being formed due to a fast monomol-ecular decay of the solutions containing the metal compounds in polymer melts—that is, in the natural voids of the polymer matrix (as PE, PP, PTFE, etc.). Such materials are called cluspol [30, 63-65], and for their production it is necessary to provide the most possible melt temperature, which must be considerably above the temperature of the carbonyl decay initiation. For this purpose the carbonyl dilute solutions are used under these conditions, providing the ultimately fast and complete removal of the split out ligand from the reaction system. Such an approach has many advantages because the temperature rise from one side promotes the metal-forming precursor decomposition and from other side decreases the by-products yield. Furthermore, in a melt (as... 

Metals and metallic compounds in polymers originate from [63, 390, 447,... 

The role of these metals and/or metallic compounds in polymer photo-oxidative degradation has been reviewed [1638, 1640,1759,1766,1768] and depends on ... 

Tomita, K., Studies on the formation of polyethylene terephthalate 6. Catalytic activity of metal compounds in polycondensation of bis(hydroxyethyl)terephthalate, Polymer, 17, 221-224 (1976). 

It is to be noted in this connection that alkyl radicals normally formed during reduction of the transition metal compound in Ziegler-Natta systems [scheme (7)] do not initiate the radical polymerisation of olefins, in contrast to that of polar monomers. Most of the modified Ziegler-Natta catalysts for polar monomer polymerisation are characterised by low activities and lack of stereospecificity, producing polymers with properties that are very similar to those of polymers obtained by more conventional procedures for radical polymerisation [28],... 

Boron compounds such as borax and boric acid are well-known fire retardants in cellulosic products and coatings.12 However, the use of boron compounds such as zinc borate, ammonium pent-aborate (APB), melamine borate, boric oxide, boron phosphate, and other metal borates in polymers has become prominent only since early 1980s.3 6 This chapter will review the chemical and physical properties, the end-use applications, as well as the mode of actions of major boron compounds as fire retardants in different applications. Since boron-based flame retardants are extensively used and quoted in literature, only those formulations of commercial importance and representative literature examples will be discussed and/or cited in this chapter. 

It has been shown that it is possible to effectively reduce the flammability of many polymeric materials by using metal compounds in very low concentrations. Metals and their compounds may be included in the polymeric macrochains, either coordi-natively bonded to functional groups of the polymer or used as additives. For example optically transparent, low-flammability polycarbonates have been obtained by adding as little as 0.001 to 2 % by weight of alkali or alkaline earth metal sulfonates... 

The polymerization of N-carboxy-a-amino acid anhydrides (Leuchs anhydrides) has also been achieved by water and by a variety of bases like amines, alkali metal hydroxides, alkali metal oxides, and organo-metallic compounds in bulk, inert solvents, or starting with the solid monomer (705). Despite a great interest in the polypeptides produced in these reactions, little attention has been paid to conditions which yield solid polymer. In case the solid was produced, no physical chemical analysis of the polymer was carried out. Pol5mierization of the crystalline monomer was already observed in 1940 705). 

It is reported that some aromatic compounds were detected in polyethylene as impurities (51, 52) although it is not clear where they came from. Aromatic molecules have absorption in the UV regions, and some kinds of aromatic molecules are known to sensitize the photodecomposition of hydrocarbons, ethers, alcohols, and polydimethylsil-oxane (53). This sensitization involves an energy-transfer process, which will be described later in some detail. The presence of radical generators, such as transition metal ions and carbonyl compounds, in polymers will also initiate photodegradation. 

Quinoid compounds are excellent acceptors of electrons and form electron donor-acceptor (EDA) complexes as a consequence of low-lying unoccupied electronic energy levels205. The EDA complexes may be easily formed in interactions with phenolic or amine components of a stabilizing mixture, with other additives which have reactive H atoms, with RO 2 radicals, or with some metallic impurities in polymers via rr-orbital interactions. Quinones efficiently participate in oxidation of polymers by virtue of these processes. 

Karasevich, E. I. Liquid-phase oxidation of alkanes in the presence of metals compounds, In Reactions and Properties of Monomers and Polymers, D Amore, A. Zaikov, G., Eds. Nova Science Publ. New York, 2007 p. 43. 

This book presents coverage of the dynamics, preparation, application and physico-chemical properties of polymer solutions and colloids. It also covers the adsorption characteristics at and the adhesion properties of polymer surfaces. It is written by 23 contemporary experts within their field. Main headings include Structural ordering in polymer solutions Influence of surface Structure on polymer surface behaviour Advances in preparations and appUcations of polymeric microspheres Latex particle heterogeneity origins, detection, and consequences Electrokinetic behaviour of polymer colloids Interaction of polymer latices with other inorganic colloids Thermodynamic and kinetic aspects of bridging flocculation Metal complexation in polymer systems Adsorption of quaternary ammonium compounds art polymer surfaces Adsorption onto polytetrafluoroethylene from aqueous solutions Adsorption from polymer mixtures at the interface with solids Polymer adsorption at oxide surface Preparation of oxide-coated cellulose fibre The evaluation of acid-base properties of polymer surfaces by wettability measurements. Each chapter is well referenced. 

C. Preparation of Metal Sols in Polymers by the Thermal Decomposition of Precursor Compounds... 

III. TRANSFORMATION OF TRANSITION METAL COMPOUNDS IN REACTIONS WITH POLYMERS... 

The transformation of transition metal compounds in reactions with polymers is difficult to study. Only a few cases have been reported. The most noticeable changes that transition metal compounds can undergo have been reduced to the following changes in metal valence state, nuclearity, and cooperativity if two or more metal complexes are involved in the reaction. 

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