Metal-Catalyzed Alkynylation of Brominated Polyphenylenes. Thermoset Precursors of High Density Monolithic Glassy Carbon
SOUTH CAROLINA UNIV COLUMBIA DEPT OF CHEMISTRY
Pagination or Media Count:
The functionalization of brominated polyphenylenes with several alkynes is described. The bromide groups on the polymer were replaced with terminal alkynes using a PdCu catalyst system. Substitution of nearly all the original bromide locations was achieved. The functionalized polymers, freely soluble in THF, exhibited high char yields of up to 89 on thermolysis to 900 deg C under a nitrogen atmosphere. Several of the functionalized polymers, derived from brominated polyphenylenes with approximately equal amounts of meta- and para-linkages, flowed on heating. The polymer that was functionalized with phenylacetylene exhibited a well-defined melting point at approximately 200 deg C and flowed to produce a monolithic disk of glassy carbon. The amount of acetylenic crosslinking units in the polymers functionalized with phenylacetylene appears to be directly related to the char yields of the functionalized polymers. Predominantly meta-linked brominated polyphenylenes were also functionalized with a number of terminal alkynes and though high char yields of up to 86 were observed, these materials offered no improvements in flow properties. The structureproperty relationships and material applications are discussed.
- Organic Chemistry
- Physical Chemistry
- Polymer Chemistry