Universal Large-Scale and Solvent-Free Surface Modification of Inorganic Particles via Facile Mechanical Grinding

Surface properties play an important role in nano/microparticles with large surface area-to-volume ratios. Even though surface modification of particles has been required in many industries in recent years, most surface modification processes are still complicated and consume large amounts of solvents, chemicals, and energy. It has a greater negative impact on the environment as the field of surface modification is rapidly growing. Herein, we present a novel solvent-free large-scale surface modification method based on grafting polysiloxanes (PSOs) onto the surfaces of inorganic particles by a simple ball milling process. PSOs containing a siloxane backbone and organic side groups have been widely used in our daily lives due to their nontoxicity, versatility, and good stability. The PSOs can react with inorganic materials in the presence of surface hydroxyl groups, grafting a few nanometer-long PSO brushes onto the surface. Using a ball mill for nano/microinorganic particles and PSOs mixtures, the particles are ground and simultaneously reacted with PSOs to modify the surface. This method allows large-scale surface modification in a single step without the use of additional solvents, chemicals, or heat, and it is applicable to most inorganic materials, including metals, oxides, and metal oxides. In addition, depending on the side groups of PSOs, the surfaces of inorganic particles have various functionalities, such as hydrophobicity and the capacity to cross-link, allowing for the fabrication of functional composite films. The ball mill-based PSO grafting strategy proposes a new environmentally friendly method for modifying and functionalizing the surfaces of inorganic particles.