Metal-containing polymers thermal decomposition

METAL-CONTAINING POLYMERS AND THEIR THERMAL DECOMPOSITION... 

Thermal decomposition of metal-containing polymer fragment ... 

Polymer-stabilized bimetallic nanoparticles containing both a light transition metal element and a precious metal element can also be prepared by a modified alcohol reduction method. For example, Cu/Pd bimetallic nanoparticles were successfully prepared with various Cu Pd ratios by refluxing a glycol solution of the hydroxides of Cu and Pd in the presence of PVP or by thermal decomposition of metal acetates. 

Copolymer 35, generated from 19 and 8, was the first transition metal containing organometaHic polymer including one metal as a r 6-complex and the other as a r 5-complex.67 The remarkable terpolymer, 37, which contains r 4-(diene)iron, T]5-(cyclopentadienyl)man-ganese, and T)6-(styryl)chromium species in each chain, was made. Thermal decomposition in air was conducted to see if mixed metal oxide particles of novel composition could be generated, but characterization of these products was beyond our capabilities in 1972. 

It was shown in [5 3,54] that there are two methods to fabricate the homogeneous polymer-immobilized dispersions of colloidal metal particles (Fe, Co, Cr, Mo, W, Mn, Re, Ni, Pd, Pt, Ru, Rh, Os, Ir) using the precursors thermal decomposition. In the former case an active polymer solution (containing amino-, amido-, imino-, nitrilo-, hydroxy-, and other functional groups) is used. In an inert solvent a labile metal compound is gradually added to the solution (this operation creates the favorable conditions for the chemisorption interaction) followed by the suspension thermal decomposition at 370-440 K or by radiation. 

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... 

The mechanism of the process is that the polymer reactive centers promote the metal nucleation and aggregation, after which the thermolysis occurs and the metal-containing substance is redistributed. The maximum amount of copper being introduced in PS through a common solvent is about 10%. At the same time, the polymer presence increases the temperature of cadmium trihydrate-oxalate decomposition [97], and the decay products increase the initial temperature of PETF intensive destruction. The copper formate thermal decomposition in the highly dispersed PETF presence allows us to produce a metallopolymeric composition (20-34% of copper) where the NP size distribution is maximal at 4nm, without any chemical interaction between the components. 

In 2010, Buchmeiser [56] developed a similar system that capitalized on the thermally reversible carboxylation [11] of NHCs (Scheme 31.13, inset). By employing the NHC-CO2 adduct (which essentially is a protected NHC), the reaction conditions did not have to be stringently air- and moisture-free to prevent NHC decomposition. Synthesis of the norbornene-functionalized monomer 37 allowed the molybdenum-catalyzed ROMP with l,4,4a,5,8,8a-hexahydro-l,4,5,8-exo-ewdo-dimethanonaphthalene (a ditopic norbornene) to produce crossHnked polymer 38 with pendant CO2-masked NHCs (Scheme 31.13). Upon heating in the presence of Rh, Ir, or Pd species, the NHC-metal-functionalized polymers 39 were formed and found to contain >20mol% metal, as determined with inductively coupled plasma optical emission spectrometry (ICP-OES). The C02-masked NHC material was found to catalyze the carboxylation of carbonyl compounds and the trimerization of isocyanates upon thermal deprotection (i.e., decarboxylation). Moreover, the NHC-metal-crosslinked materials were found to catalyze Heck reactions, transfer hydrogenations, and also the polymerization of phenylacetylene (M = 8.4 kDa, PDI = 2.45, as determined with GPC in DMF against PS standards). This modular system provides an array of options for catalysis from simple modifications of polymer-supported, C02-masked NHCs. 

The Claspols (Section V.3) are obtained by the thermal decomposition of metal salts and carbonyls in polymers melts (PE, PTFE, etc.). Particles appear in Claspols that reduce the mobility of molecular chains, thereby increasing the thermal resistance of polymeric compositions. As noted above, the decomposition of a fine palladium hydroxide dispersion in PVC leads to the formation of network structures. These networks contain the highly dispersed metal in their PVC encapsulated knots. 

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