Polymer anchoring layer for atomic force microscopy studies of nanoparticle-substrate interactions

An immiscible polymer blend of poly(glycidyl methacrylate) and poly(vinylpyridine), PGMA/PVP, was used as an anchoring layer to attach silica nanoparticles to an oxidized silicon wafer surface. The stability of the arrays of colloidal particles was studied in pH 4 and pH 10 buffer solutions, deionized (DI) water, and nonionic surfactant solution. The array was determined to be stable. Attachment of the nanoparticles to one-component homogeneous PGMA and PVP films was also studied in order to determine the role of each polymer in the anchoring layer. Virtually no particles were adsorbed on the surface modified with PGMA. The nanoparticles could be adsorbed on PVP, but the integrity of the polymer layer was destroyed in the environment used for adsorption, i.e., a dispersion of nanoparticles at pH 10. Measurement of adhesion between the nanoparticles attached to the anchoring layer and the glass substrate were performed in aqueous media having different pH values using a colloidal probe atomic force microscopy (AFM) technique.