Fine and Nanoparticle Adhesion and Aggregation Behaviour Characterisation and Control

The control of adhesion and aggregation behaviour in gases, liquids, and solids is important for the application of inorganic nano- and fine particles in various fields, such as functional materials and devices, pharmaceuticals, cosmetics, and pigments. We have developed original methods for the characterisation of interfacial molecular- and nanometre-scale structures and interactions between particles and substrate materials. The surface molecular-structure design by an organic surfactant, commonly called a “ligand,” was investigated with different molecular structures for nanoparticle-dispersion stability control in various organic solvents and polymer solid materials. First, we introduce various approaches for controlling the interfacial molecular structure of nanoparticles to disperse nanoparticles in various liquids. Next, aggregation- and adhesion-behaviour characterisation methods, such as colloid probe atomic force microscopy and the control of fine powders and microcapsules in the ceramic and pharmaceutical fields, are reviewed. Finally, the characterisation and control of the adhesion behaviour of fine ash particles at high temperatures in energy generation and environmental systems are investigated. Original characterisation devices and a model of an ash-particle preparation method from pure silica were developed by adding small amounts of elements, such as alkali metals and phosphates, to analyse the increase mechanism of the ash-adhesion force at high temperatures. Based on the results of the analysis, the adhesion behaviour can be controlled by the addition of various materials.