Morphology and production mechanism of the functionalized carboxylate alumoxane micro and nanostructures

Four types of carboxylate alumoxanes, namely, para hydroxybenzoate alumoxane (PHBA), salicylate alumoxane, para aminobenzoate alumoxane (PABA) and fumarate alumoxane were successfully synthesized from boehmite nanoparticles and the corresponding carboxylic acids and characterized, two of which (salicylate and fumarate-alumoxanes) have not been reported in the literature so far. Boehmite nanoparticles were used as the starting material. The structures were characterized, using FTIR, SEM, TEM and TG-DTA. Mechanisms were proposed for the formation of the synthesized structures. TEM micrographs of salicylate alumoxane confirmed the morphologies such as nano-sheets, nanorods and nanoribbons. Nanothreads were observed in the TEM micrographs of fumarate alumoxane. Cubic agglomerates of fumarate alumoxane were detected. PHBA with structures similar to hexagonal prism were detected. Mechanisms were proposed for the formation of these products. Microstructure analysis explained well the experimental parameters obtained from thermal analysis. [Display omitted] ► Four carboxylate alumoxanes micro and nanostructures were synthesized. ► Fumarate and salicylate alumoxanes were synthesized for the first time. ► Prepared alumoxanes have morphologies such as sheet, rod, prism, ribbon and cube. ► The preparation mechanisms of alumoxanes were identified. ► Resultant alumoxanes have more thermal stability than boehmite precursor.