Organometallic polymers, thermal

Pincer compounds with a general structure like 20 are common in organo-metallic chemistry [832]. They are useful as precursors to catalysts and as components of hybrid organometallic polymers [84-86]. In most cases, they have high stability to oxygen and water in addition to high thermal stability. 

R. B. Seymour, Modern Plastics Technology, Chapter 15, Reston Publishing, Reston, Va. (1975). C. E. Carraher, Thermal characterizations of inorganic and organometallic polymers, J. Macromol Sci, Chem. A17(8), 1293-1356 (1982). 

Synthetic strategy has been developed that permits the efficient preparation of organometallic polymers which have structural characteristics necessary for nonlinear optical behavior. Complex t 5-C5H4CH20H - i 5-C5H4CH=C(CN)C02Et Fe (4) was prepared and homopolymerized through a thermally induced transesterification-polycondensation reaction. 

The advantage of these polymers over poly(vinylferrocenes) or related species with pendent organometallic units is that the condensation polymers have ferrocene units in the main chain where they can exert their maximum influence on polymer thermal stability. The disadvantage of the condensation products is that, except in the last example, the molecular weights are too low to favor fiber or flexible film formation. Nevertheless, this work indicated the potential usefulness of polymers with metallocene units in the main chain. 

Materials science applications have driven a vigorous search for new organometallic compounds, both molecular3 and polymeric,4 as precursors for new materials. In the case of polymers, this interest is driven by two different end applications. The first is the intrinsic properties of the materials, such as their electronic, photonic, or thermal/mechanical properties. The second is their use as precursors to purely inorganic materials. Organometallic polymers are particularly attractive precursors because of the inherent ease and versatility that they exhibit with regard to processing. 

Metallic species such as iron, nickel and cobalt are known to catalyze the growth of CNTs in the CVD process [168-170]. Because of the ready thermal curability of the hb-PYs, spin-coated films of organometallic polymers 81 and 82 are expected to restrict the agglomeration of the metallic nanoclusters in the CVD process and hence to provide nanoscopic catalyst seeds for the... 

Boron-containing, Non-oxide Ceramics from Organometallic Polymers Synthesis, Thermolysis and the Influence of Boron on Materials Thermal Stability... 

The fibers are produced continuously (endless fibers, filaments) or discontinuously (short or staple fibers) depending upon the application. Most of the fibers are obtained by extruding a flowable form (melt or solution) of appropriate chemieal composition (Section 5.2.3 - 5.2.4). Other processes are based on deposition from the gas phase (Section 5.2.6.2) or thermal transformation (pyrolysis) of organic (Section 5.2.5) or organometallic polymers (Section 5.2.7). 

Examples of organometallic polymers containing both phosphorus atoms and transition metals in the backbone include polyferrocenylphosphines 8 (and the corresponding phosphine sulfides 9), which are accessible via the thermal ROP of phosphorus-bridged [1] ferrocenophanes [16,17]. Polymers of this type have been previously prepared by condensation routes and the catalytic potential of some of their transition metal derivatives has already been noted [18]. Living anionic ROP of phosphorus-bridged [l]ferrocenophanes has recently been demonstrated and provides a route to block copolymers such as 10 (PI = poly-isoprene) [19] ... 

The structure and thermal behavior of two organometallic polymers, poly (ferrocenyl dimethylsilane) (I) and poly(ferrocenyl di-n-butylsilane) (II), have been characterized by solid-state C NMR spectra acquired for a wide range of contact times. ... 

The topic of thermal characterizations of inorganic and organometallic polymers was recently reviewed by the author in a comprehensive review... 

Many organometallic polymers undergo initial thermal degradation through solid transitions without melting. 

Thus the presence of trace amounts of nucleophilic or electrophilic agents can lead to a dramatic decrease in the thermal stability of organometallic polymers. This becomes increasingly important when it is remembered that many polymerizations employ such reagents as catalystic agents and even less recognized is the presence of such impurities in the monomers themselves. 

Chujo and co-workers made conjugated organometallic polymers containing platinum and tricarbonyl(arene)chromium moieties.200 (T)6-l,4-Diethynylbenzene)tricarbonylchromium reacted with /ran.v-fPBu.bPtCT in the presence of Cul produced copolymer 116 with A/w = 31,700 and PDI = 1.9. Analysis of the polymer showed 70% incorporation of chromium blocks and 30% uncoordinated phenylene units. Thermal analysis showed two... 

Ring-opening polymerization (ROP) has seen broad utility for synthesizing main-chain organometallic polymers. Initially reported by Rauchfuss [9], and thoroughly developed by Manners and coworkers [10], the transformation from 10 to 11 (Schane 1.4) has been optimized to include various conditions for polymerization such as thermal, anionic, photo, and metal-mediated polymerizations Both solution and solid-state polymerization have also been reported. Molecular weights on the order of 10 Da have been achieved and the ability to prepare monomers of varying functionahty has assisted... 

Interest in organometallic maaomolecules has grown exponentially ever since Arimoto and Haven first polymerized vinylferrocene in 1955 [1]. Organometallic polymers are known to possess unique optical, magnetic, and thermal properties which allow for potential applications as chemical sensors, electrocatalysts, modified electrodes, and photo-active molecular devices [2-7]. Organoiron polymers are one of the most prevalent classes of organometallic polymers, with many reports on their synthesis and properties published over the past 50 years [8-11]. Of the many varieties of organoiron species, ferrocene and cationic cyclopentadienyliron complexes are most commonly incorporated into polymers. 

Polysiloxanes are macromolecules with alternating silicon and oxygen atoms in the backbone. Polysiloxanes or silicone polymers are the most important organometallic polymers. They are characterized by combinations of excellent chemical, mechanical, and electrical properties. Polysiloxanes exhibit relatively high thermal and oxidation stability, high dielectric strength, and low power loss. They are relatively inert to most ionic reagents. 

---