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

Abstract

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 does not utilize toxic reagents or volatile organic chemicals (VOCs); the aqueous synthesis of "water-soluble" carboxylate-alumoxane precursors from inexpensive boehmite feed stock. Carboxylate-alumoxanes, [Al(O) x (OH) y (O 2 CR) z ] n , were synthesized by the reaction of boehmite, [Al(O)(OH)] n , with acetic acid (HO 2 CCH 3 ), methoxyacetic acid (HO 2 CCH 2 OCH 3 ), (methoxyethoxy)acetic acid (HO 2 CCH 2 OCH 2 CH 2 OCH 3 ) and [(methoxyethoxy)ethoxy]acetic acid [HO 2 CCH 2 (OCH 2 CH 2 ) 2 OCH 3 ]. Carboxylate-alumoxanes are infinitely stable at ambient conditions in solid and solution. In addition, they show no propensity to segregation or polymerization 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 have been determined, including particle size, molecular weight, hardness, refractive index and dielectric constants. The application of the carboxylate-alumoxanes as preceramic binders in traditional tape casting, and infiltration agents has been demonstrated. The potential environmental impact of the new alumoxane methodology as compared to traditional approaches will be discussed.

Enhanced cyclability of LiCoO2 cathodes coated with alumina derived from carboxylate?alumoxanes

“…Carboxylate-alumoxane precursors were prepared according to procedures described by Callender et al [22]. A commercial sample of boehmite, [Al(O)(OH)] n (Catapal B, average particle size: 60 lm; BET surface area: 240 m 2 g )1 ), was used.…”

“…Carboxylate-alumoxanes, represented by the general formula [Al(O) x (OH) y (OOCR) z ] n , are formed when the mineral boehmite, [AlO(OH)] n , reacts with a carboxylic acid according to the reaction [22,23] […”

“…The carboxylate ions 'unzip' the boehmite structure, abstract, and stabilize nanoparticulate fragments of boehmite by replacing its oxide and hydroxide groups with acid groups [22][23][24]. Thermolysis of carboxylate-alumoxanes yields alumina [24,25].…”

“…Thermolysis of carboxylate-alumoxanes yields alumina [24,25]. The nature of the carboxylate-alumoxanes depends on the identity of the carboxylic acid used [22]. Thus, we should expect the characteristics of the alumina product to be dependent on the precursor.…”

Alumoxane/ferroxane nanoparticles for the removal of viral pathogens: the importance of surface functionality to nanoparticle activity

“…S4 †) results in the partial loss of functional groups on the nanoparticles without sintering of the individual nanoparticles and lowering the surface area. 14,25 This suggests that the surface functionalization of the nanoparticles (i.e., the hydrophilic surface due to the cysteic acid functional groups) is vital for the surface collapse of aspirated water droplet and the subsequent absorption and immobilization of the MS2 viruses. Thus we can conclude that a nanoparticle surface functionalization is far more important in the present process than the actual nanoparticle nature of the coating per se.…”