Organic Modification of Hydroxylated Nanoparticles: Silica, Sepiolite, and Polysaccharides

Abstract

The incorporation of organic compounds onto the surface of nanoparticles (NPs) differs from the same reactions carried out on macroscopic surfaces in that the former are characterized by surfaces energies much higher than the latter. Consequently, surface stabilization mechanisms of NPs are very active, and among them NP self-aggregation is the first and most important. In NP surface modification, the ability of the experimental conditions to destroy self-aggregation will determine the extent to which the NP surface is modified and so, the modified NP nature. A second consequence of the high-surface free energy is the NP surface avidity to interact chemically or physically with other compounds: NPs readily adsorb water, gases, vapors, or other higher molecular weight substances, and in the particular case of hydroxylated NP, chemical reactivity is both high and rich. This chapter will deal with the surface modification of silica, sepiolite, and polysaccharides. Experimental strategies, resulting organo-NPs, their structure and properties, and frequent uses and applications of them will be reviewed.