INFRARED SPECTROSCOPIC INVESTIGATION OF CHEMISORPTION ON CHEMICALLY SYNTHESIZED ALUMINUM NITRIDE NANOPOWDERS WITH 2-PYRROLIDINONES

The chemical nature of a nanoparticle surface is of crucial importance in controlling the interparticle forces during powder processing. As a continuation of a FT-IR spectroscopy study on the surface chemical s tructure of the chemically synthesized aluminum nitride (AW) nanopowde rs, the adsorption of two representative cyclic amides, i.e., N-methyl -2-pyrroldinone (NMP) and 2-pyrrolidinone (NHP), have been investigate d Upon adsorption of these cyclic amides, strong hydrogen bonding betw een the amide carbonyl oxygen and the surface hydroxyl groups was evid ent. The unusual thermal stability for the hydrogen bonding observed w ith NMP was explained as being due to the enhancement by secondary int eractions between the NMP amide carbonyl group and the surface Lewis a cidic sites, such as Al3+. With the adsorption of NHP at room temperat ure, besides the formation of strong hydrogen bonding, a striking 100 cm(-1) shift to higher wavenumbers was observed for both the carbonyl and amide C-N stretching bands. This has been interpreted as the forma tion of complex coordination between the amide nitrogen and the surfac e acidic sites. The amide N-coordinated complex plus the carbonyl O-co ordinated hydrogen bonding promote a synergistic effect for strengthen ing the NHP adsorption on the AIN surface.