Precursors polymeric

To be a suitable precursor for vitreous carbon, a polymer must have the following characteristics 1 

The following polymeric precursors are, or have been, used in production or experimentally.PlPl 

Polyfurfuryl alcohol Polyfurfuryl alcohol is a thermosetting resin which is obtained by the polymerization of the furfuryl-alcohol monomer catalyzed with maieic acid, its chemical structure is the following  

In addition to being a precursorfor vitreous carbon, polyfurfuryl alcohol is also a common impregnant for graphite electrodes (see Ch. 5). 

Phenollcs. Phenolics, typically (Ci502H2o)n, are a class of polymers which are obtained by a condensation reaction, usually between phenol auid formaldehyde, with elimination of water. The monomer has the following chemical structure  

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It has been shown that hydrogen bonding-mediated interpolymer complexes can be powerful drag reducers. The drag-reduction levels in such polymer systems increase dramatically by a factor of 2 to 6 when compared with their nonassociating polymeric precursors. Their shear stability is also shown to be significantly enhanced [1156]. 

Another process for silicon carbide fibers, developed by Verbeek and Winter of Bayer AG [45], also is based on polymeric precursors which contain [SiCH2] units, although linear polysilmethylenes are not involved. The pyrolysis of tetramethylsilane at 700°C, with provision for recycling of unconverted (CHg Si and lower boiling products, gave a polycarbosilane resin, yellow to red-brown in color, which was soluble in aromatic and in chlorinated hydrocarbons. Such resins could be melt-spun but required a cure-step to render them infusible before they were pyrolyzed to ceramic... 

The Yajima polycarbosilane, while it was one of the first, is not the only polymeric precursor to silicon carbide which has been developed. 

Another useful system which merits mention is the polycarbosilane which resulted from research carried out by C.L. Schilling and his coworkers in the Union Carbide Laboratories in Tarrytown, New York [6]. More recently, a useful polymeric precursor for silicon nitride has been developed by workers at Dow Corning Corporation [7]. 

In this study, we extend the range of inorganic materials produced from polymeric precursors to include copper composites. Soluble complexes between poly(2-vinylpyridine) (P2VPy) and cupric chloride were prepared in a mixed solvent of 95% methanol 5% water. Pyrolysis of the isolated complexes results in the formation of carbonaceous composites of copper. The decomposition mechanism of the complexes was studied by optical, infrared, x-ray photoelectron and pyrolysis mass spectroscopy as well as thermogravimetric analysis and magnetic susceptibility measurements. 

Chlorination of the polymeric precursors. A two-liter jacketed glass... 

C. Polymeric Precursors Derived from tris(Borylamino)borazines 112... 

By analogy with B-trialkylaminoborazi ne and polyborazine derived therefrom, the first route envisioned to poly(borylaminoborazine) was the thermal condensation of molecular precursors under a convenient atmosphere. As detailed earlier the innovative idea behind this procedure is to tailor the polymeric precursor structure by increasing the distance between the two borazinic rings. For that purpose, we explored... 

The spectrum of silicon based polymers is enriched by high tech ceramics like silicon nitride and carbide, respectively. These materials are produced by pyrolysis of appropriate polymeric precursors such as polysilanes, polycarbosilanes and polysilazanes (preceramics). These synthetic ceramics display a certain analogy to silicates, having SiC, SiN, or Si(C,N) as structural subunits instead ofSiO. 

Report 76 Polymeric Precursors for Ceramic Materials, R.C.P. Cubbon. 

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