Poly -derived ceramic

Morcos, R. M., Navrotsky, A., Varga, T., Blum, Y., Ahn, D., Poli, F. et al. (2008). Energetics of Si O C polymer-derived ceramics prepared under varying conditions. 

Borazine is isoelectronic and isostructural with benzene. Poly(borazylene), a polymer of borazine and its derivatives, is reported extensively as a precursor of BN-coated ceramic libers.86 Polymeric borazine oxide derivative is claimed to be flame resistant (Figure 9.10).87... 

Characterization, Characterization work at all stages of fiber processing, as illustrated in Figure 1, is important. The discussion in this chapter will be limited to certain aspects of polymer and ceramic fiber characterization, which will be illustrated with poly(methylsilane) (MPS) and HPZ polymers and the ceramic fibers derived from these polymers. 

Figure 2. X-ray diffractograms of powdered ceramic fibers (Cu K2). CGN is ceramic-grade Nicalon, and SGN is standard-grade Nicalon. MPDZ-PhVi is poly(methyldisilylazane)-derived fiber. See reference 21 for complete details.

Polymeric precursors have been developed which are stable at room temperature and when polymerized convert to ceramics in high yield. Such precursors may be synthesized by reaction of a vinylsilane, vinylmethylsilane, acetylene silane, or acetylene alkyl silane with a borane or a borane amine derivative The reactants are mixed in an inert atmosphere, either neat or in an aprotic solvent like acetonitrile, tetrahydrofuran, or a hydrocarbon, or in a mixture of such solvents. The reaction mixture is heated for 0.1 to 120 h at 90-170°C. The solvent, if any, is then removed. The polymer is pyrolyzed in argon or N2 at SOO-ISOO C for 1 h. BN and other ceramics such as B4C, or SipB QNs compounds can be made, where p, q, r, and s have various numerical values. To date, no measurements of the crystallographic form of the resultant BN compound have been made. Other precursors convertible to BN include poly (2-vinylpentaborane) oligomers. ... 

It has been confirmed that the presence of bridge-type bonds in such poly (B-alkylaminoborazines) confers flexibility and an inaeased melt-spirmability, thus leading to the conclusions that melt-spinnability inaeases from 1- to 4-daived polymers. In addition, the ceramic yield is reduced with the increased proportion of -NlCHj) in the B-(alkylamino)borazine leading to important shrinkages during the furlha- polymer-to-ceramic conversion of green fibers derived therefrom. Hence, it is relevant to assume... 

Berger, F, Muller, A., Aldinger, F., and Muller, K. Solid-state NMR investigations on Si-B-C-N ceramics derived from boron-modified poly(allylmethylsilazane). 

Mera, G., Riedel, R., Poll, R, and Muller, K. Carbon-rich SiCN ceramics derived from phenyl-containing poly(silylcarbodiimides). ]jggCeram ,5oc. 2009 29 2873-2883. 

Abstract - Studies of the syntheses, properties and ceramic conversion reactions of the new processable borazine-derived polymer systems, poly(vinylborazine), poly(vinylborazine/styrene) and poly(borazylene), along with selected applications of these polymer precursors for the formation of boron nitride ceramics are described. 

---