SYNTHESIS AND CHARACTERIZATION OF PROCESSABLE POLYBORATE PRECURSORS

Polyborates have been formed by disproportionation and polycondensatio n of trimethoxyboroxine and also of trimethoxyboroxine and boric acid. The critical role of stoichiometry in the formation of polyborates wi thout requiring incorporation of a metal counter ion is revealed. The emphasis is on integration of this chemistry with fabrication processe s. Incorporation of an appropriate linear organic polymer is shown to yield the required theological and thermal characteristics in this reg ard. These polyborates are inferred to be suitable as precursors for b oron nitride in geometrical forms that can be processed as supported s tructures. However, they are also determined to be unsuitable as precu rsors for boron nitride fibers, oriented or isotropic, primarily due t o their low glass transition temperature.