Dispersive forces of particle–surface interactions: direct AFM measurements and modelling

• Published in: Powder technology Vol. 130; no. 1; pp. 102 - 109
• Main Authors: Götzinger, Martin, Peukert, Wolfgang
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 19-02-2003; Elsevier
• Subjects: Adhesion; Adsorption; AFM measurements; Alumina; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; van der Waals forces; AFM measurements; Adsorption; van der Waals forces; Adhesion; Alumina; Atomic force microscopy; Interparticle interaction; Roughness; Theoretical study; Van der Waals interaction; Particle interaction; Experimental study; Modeling; Surface energy
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/S0032-5910(02)00234-6

Fundamentals of particle–particle interaction are of great interest in agglomeration processes. Particle adhesion depends on dispersive forces (van der Waals force), local chemical bindings, Coulomb force and capillary attractions. Additionally, surface properties like roughness, adsorption layers and surface chemistry strongly affect adhesion forces. van der Waals interactions are poorly understood because popular ab initio force calculations for molecules like density functional theory (DFT) often do not lead to proper results. van der Waals forces are difficult to measure directly. We present direct measurements of particle–particle and particle–surface interactions in the gas phase carried out with an atomic force microscope (AFM). Special emphasis is given to a proper statistical treatment of the data. For modelling of particle adhesion, we use computer-assisted empirical potential methods. Parameters like adsorbed water and surface roughness are considered. We extract parameters for weak interactions from the Lifshitz theory and gas adsorption data. Adsorbing molecules can be used as probes to measure dispersive forces. Studying surface and particle properties combined with computer-assisted modelling is a basic requisite to reach the aim of predicting particle–particle interactions in industrial processes.