Adhesion between Oxide Nanoparticles: Influence of Surface Complexation

Attachment of nanoparticles to the AFM tips for direct measurements of interaction between a single nanoparticle and surfaces

“…2 and 3). As was noted [14], the number of reactive sites Ce*-OH on ceria surface increases with the increase of pH. This could explain that the adhesion stays almost the same despite the decrease of attractive electrostatic force, the case of Opaline with pH 4-9 and Nanophase ceria with pH 4-6.…”

“…However, there is a competing process. The increase of pH (to the isoelectric point) leads to hydroxylation (Ce*-OH + OH − → Ce-(OH) − 2 ) and deactivation of the reactive sites [14]. So, it would not explain the increase of adhesion for Nanophase ceria at pH 9.…”

“…Chemical modification of ceria surface in presence of nitrate ions has been studied in Refs. [13,14]. Above pH 3 some nitrate ions are strongly (non-electrostatically) bound to ceria "reactive" sites (Ce*) and gradually released via the exchange reaction,…”

From Heterocoagulation to Biorecognition: Preparation of Surfaces for Direct Measurement of Their Interactions in a Surface Force Apparatus

“…Indeed many situations may arise and have already been clearly identified by our previous investigations in several systems. Adsorbed particles may deform or be displaced (rolling laterally along the substrate, being pushed aside, or being desorbed) under applied loads . Similarly contact of one coated‐mica surface with another opposite surface (bare or coated substrate) may deform fragile supported objects such as phospholipids membranes or polyelectrolyte multilayers: elastic and even plastic irreversible deformation may be observed as the signature of interpenetration of the multilayers under compression .…”

“…Similarly contact of one coated‐mica surface with another opposite surface (bare or coated substrate) may deform fragile supported objects such as phospholipids membranes or polyelectrolyte multilayers: elastic and even plastic irreversible deformation may be observed as the signature of interpenetration of the multilayers under compression . Finally transfer of material from one surface onto the opposite one may occur depending on the strength of the mutual adhesion energy between particles or adjacent films compared to the adhesion energy between the adsorbed particles or the film with the substrate . In such a case when the two adjacent layers adhere more strongly to each other than they adhere to the walls, patchy surfaces will be formed after separation: each surface will end up as being comprised of void domains where parts of the initial adsorbed layer have been transferred to the other surface, and of thick domains conversely made with two juxtaposed adsorbed layers parts.…”