Synthesis, properties, and ceramic conversion reactions of polyborazylene. A high-yield polymeric precursor to boron nitride
- Univ. of Pennsylvania, Philadelphia, PA (United States); and others
Borazine readily dehydropolymerizes at moderate temperatures (70-110 {degrees}C) to give a soluble polymer, polyborazylene, in excellent yields of 81-91%. The polymer is isolated as a white solid that is soluble in ethers such as glyme and THF. The polymer can be precipitated by slowly adding ether solutions of the polymer to pentane. Powder X-ray diffraction suggests the presence of a layered structure for the polymer in the solid state, which is consistent with its observed density of 1.5-1.6 g/cm{sup 3}. Molecular weight studies using size exclusion chromatrography (SEC)/viscometric detection (VISC) give accurate determinations of a lower value of M{sub n}, 500-900 g/mol. SEC/low-angle laser light scattering (LALLS)/ultraviolet absorbance (UV) give determinations of M{sub 2} biased toward high molecular weights, with values usually between 3000 and 8000 g/mol. The combined spectroscopic and molecular weight data indicate that the polymer appears to have a complex structure, having linear, branched-chain and fused-cyclic segments, related to those of the organic polyphenylenes. Pyrolysis studies show that the polymer converts to boron nitride in excellent yield. 44 refs., 21 figs., 8 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 379375
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 10 Vol. 7; ISSN CMATEX; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
Similar Records
Molecular weights of lignite macromolecules
Synthesis, characterization, and ceramic conversion reactions of borazine-modified hydridopolysilazanes: New polymeric precursors to SiNCB ceramic composites