AQUEOUS SYNTHESIS OF WATER-SOLUBLE ALUMOXANES - ENVIRONMENTALLY BENIGN PRECURSORS TO ALUMINA AND ALUMINUM-BASED CERAMICS

The objective of our research is the development of an environmentally benign process for the fabrication of alumina-based ceramics. We have designed an alternative synthetic pathway to alumina ceramics that do es not utilize toxic reagents or volatile organic chemicals (VOCs); th e aqueous synthesis of ''water-soluble'' carboxylate-alumoxane precurs ors from inexpensive boehmite feed stock. Carboxylate-alumoxanes, [Al( O)(x)(OH)(y)(O2CR)(z)](n), were synthesized by the reaction of boehmit e, [Al(O)(OH)](n), with acetic acid (HO2CCH3), methoxyacetic acid (HO2 CCH2OCH3), (methoxyethoxy)acetic acid (HO2CCH2OCH2CH2OCH3) and [(metho xyethoxy)ethoxy] acetic acid [HO2CCH2(OCH2CH2)(2)OCH3]. Carboxylate-al umoxanes are infinitely stable at ambient conditions in solid and solu tion. In addition, they show no propensity to segregation or polymeriz ation and are readily processed in aqueous or hydrocarbon medium. Upon thermolysis the carboxylate-alumoxanes are converted to alumina. The physical and spectroscopic properties of the carboxylate-alumoxanes ha ve been determined, including particle size, molecular weight, hardnes s, refractive index and dielectric constants. The application of the c arboxylate-alumoxanes as preceramic binders in traditional tape castin g, and infiltration agents has been demonstrated. The potential enviro nmental impact of the new alumoxane methodology as compared to traditi onal approaches will be discussed.