Inorganic−Organic Hybrid and Composite Resin Materials Using Carboxylate-Alumoxanes as Functionalized Cross-Linking Agents

Chemically functionalized alumina nanoparticles (carboxylate-alumoxanes) are used as the inorganic component of a new class of inorganic−organic hybrid materials. Lysine- or p -hydroxybenzoic acid-derivatized alumoxanes are readily prepared from the reaction of boehmite, [Al(O)(OH)] n, with the appropriate carboxylic acid. The peripheral organic hydroxides and amines of these carboxylate-alumoxanes either react directly with epoxide resins, such as the diglycidyl ether of bisphenol A (DER 332), to form a hybrid material, or in the presence of an organic resin and hardener system to form a composite material. SEM with associated EDX analysis, and AFM shows a uniform distribution of alumina nanoparticles within the resin matrix. Solid-state 13 C and 27 Al NMR spectroscopy demonstrates that the carboxylate-alumoxane nanoparticles are chemically bound to the epoxide resin matrix. The model compounds PhOCH 2 CH(OH)CH 2 OPh ( 1 ), PhOCH 2 CH(OH)CH 2 NH n Pr ( 2 ), and PhOCH 2 CH(OH)CH 2 NH i Pr ( 3 ) have been prepared to assist in the NMR characterization of the hybrid materials. The properties and cure times of the alumoxane hybrid and composite materials are distinct from both the pure resins and from a physical blend of the resins with traditional ceramic fillers. A significant increase in thermal stability and tensile strength is observed for both the hybrid and composite resin systems. In addition, both carbon fiber and carbon/Kevlar matting have been successfully incorporated into the hybrid resin systems resulting in further property improvements.