Synthesis, functionalization and characterization of silica nanoparticles for surface metal electrografting

M. JOSELEVICH; F. J. WILLIAMS

Buenos Aires, Argentina

Simposio; 15th International Symposium on Metastable, Amorphous and Nanostructured Materials; 2008

Metal and semiconductor surfaces are functionalized with nanoparticles (nps) to add new properties such as superhydrophobicity [1,2] and corrosion protection [3]. Various techniques have been developed to bind nps to surfaces but most of them result in weak nanoparticle-surface interaction [4]. Covalent binding of nps to surfaces has recently been achieved by a method that involves functionalization of both the surface and the nps [5,6]. Furthermore, molecular species that contain diazonium functionalities can be covalently bonded to surfaces by electrochemical reduction [7] without prior surface functionalization. Therefore we expect that nps which are surface functionalized with diazonium groups could be covalently bonded to surfaces electrochemically. In this work, we synthesized ~140 nm silica nps surface-modified with diazonium groups using a four-step functionalization route. Steps involved subsequent np-surface modification to give (i) amine, (ii) carboxylic acid (iii) aniline and (iv) diazonium organic functionalities. All reaction steps were followed with IR and XPS and the structure of the diazo-functionalized np was confirmed with solid state NMR. Finally, nps were bonded to gold surfaces by electrografting. Np-surface attachment was confirmed by XPS, AFM and SEM.