Particle film (particulate film or granular film) based emulsions have attracted great attention because they are widely used in oil, paper, food, cosmetics, pharmaceuticals and other fields. This paper summarizes the characteristics of film-forming particles on the oil-water interface such as density, size and wettability, and expounds the adsorption and diffusion of particles on the oil-water interface. The structures of particle film are highlighted, including the distribution and orientation of particles perpendicular to the interface, the arrangement of particles on the oil-water interface and the spatial structures of film. The influencing factors of the state of particles on the oil-water interface as well as the particle film structures are summed up, then the nature of them is analyzed from the aspects of energy and mechanics. The mechanism of particle film stabilizing emulsion is elucidated from the structures of particle film and the interfacial viscoelasticity. The particle film hinders the collision and coalescence between the dispersed droplets, which is the basis of stable emulsions. Meanwhile, strengthened interfacial viscoelasticity makes sure the particle film will not easily collapse during dispersed droplets' movement, collision and flocculation. The mechanism of solid particles stabilizing emulsion as emulsifiers provides a theoretical basis for not only the preparation of stable emulsions but also the demulsification of emulsions, which is of important realistic significance. At last, we propose prospects of future development and possible solutions of the study on the mechanism of particle film stabilizing emulsion.

Contents
1 Introduction
2 The formation of particle film
2.1 The sources of particles
2.2 The characteristics of particles
2.3 The adsorption and diffusion of particles on the oil-water interface
3 The structures of particle film
3.1 Distribution and orientation of particles perpendicular to the interface
3.2 Arrangement of particles on the oil-water interface
3.3 Spatial structures of particle film
4 The mechanism of particle film stabilizing emulsion
4.1 The impact of particle film’s structures on emulsion stability
4.2 The impact of interface viscoelasticity on emulsion stability
5 Conclusion