Design of Pickering Micro- and Nanoemulsions Based on the Structural Characteristics of Nanocelluloses.

The development of biobased materials with lower environmental impact has seen an increased interest these last years. In this area, nanocelluloses have shown a particular interest in research and industries. Cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) are both known to stabilize oil-water interfaces, forming the so-called Pickering emulsions which are surfactant-free, highly stable emulsions armored by a layer of solid particles. This work describes the emulsion's characteristics and properties according to particle size, shape and surface chemistry in order to produce controlled micro- and nanoemulsions stabilized by nanocelluloses. For this purpose, four nanocelluloses which vary in source, length, width, and surface charge density were used. Isolated droplets were produced by CNCs and interconnected droplets by CNFs that led to distinct drop size (micro- and nanosized), organization of nanoparticles at the surface of the droplets, stability, and mechanical properties through rheological measurements. This work gives a precise description of the resulting emulsions and shows the ability to produce nanosized droplets for CNC and TEMPO oxidized CNF but not for the less fibrillated CNF using HP-homogenizer. Individual noncreaming droplets with average diameters as low as 350 nm were achieved for cotton CNCs and TEMPO oxidized CNFs.