Aqueous Synthesis of Water-Soluble Alumoxanes: Environmentally Benign Precursors to Alumina and Aluminum-Based Ceramics

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• 作者：Rhonda L. Callender ; C. Jeff Harlan ; Noah M. Shapiro ; Christopher D. Jones ; Daniel L. Callahan ; Mark R. Wiesner ; D. Brent MacQueen ; Ron Cook ; and Andrew R. Barron
• 刊名：Chemistry of Materials
• 出版年：1997
• 出版时间：November 1997
• 年：1997
• 卷：9
• 期：11
• 页码：2418 - 2433
• 全文大小：2067K
• 年卷期：v.9,no.11(November 1997)
• ISSN：1520-5002

文摘

The objective of our research is the development of anenvironmentally benign process forthe fabrication of alumina-based ceramics. We have designed analternative syntheticpathway to alumina ceramics that does not utilize toxic reagents orvolatile organic chemicals(VOCs); the aqueous synthesis of "water-soluble"carboxylate-alumoxane precursors frominexpensive boehmite feed stock. Carboxylate-alumoxanes,[Al(O)_x(OH)_y(O₂CR)_z]_n,weresynthesized by the reaction of boehmite,[Al(O)(OH)]_n, with acetic acid(HO₂CCH₃),methoxyacetic acid(HO₂CCH₂OCH₃),(methoxyethoxy)acetic acid(HO₂CCH₂OCH₂CH₂OCH₃)and [(methoxyethoxy)ethoxy]acetic acid[HO₂CCH₂(OCH₂CH₂)₂OCH₃].Carboxylate-alumoxanes are infinitely stable at ambient conditions in solid andsolution. In addition, theyshow no propensity to segregation or polymerization and are readilyprocessed in aqueousor hydrocarbon medium. Upon thermolysis thecarboxylate-alumoxanes are converted toalumina. The physical and spectroscopic properties of thecarboxylate-alumoxanes havebeen determined, including particle size, molecular weight, hardness,refractive index anddielectric constants. The application of thecarboxylate-alumoxanes as preceramic bindersin traditional tape casting, and infiltration agents has beendemonstrated. The potentialenvironmental impact of the new alumoxane methodology as compared totraditionalapproaches will be discussed.