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

Abstract

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.

Oil-in-Water Emulsions Stabilized by Cellulose Nanofibrils—The Effects of Ionic Strength and pH

“…The mastersizer is not able to distinguish between individual droplets and aggregates of smaller droplets. Consequently, some of the sizes measured could correspond to this type of aggregates as previously has been shown with TEMPO-CNF-stabilized emulsions [21]. Low charge CNFs, such as bacterial cellulose, have been shown to give emulsions that are stable against changes in pH and ionic strength [14,17].…”

“…These studies ranges from highly charged finely fibrillated TEMPO-oxidized CNFs to less charged bacterial cellulose, enzymatically treated, and to coarser, purely mechanically disintegrated CNFs [13,14,15,16,17,18,19,20]. Saelices and Capron have compared the features of emulsions stabilized by four types of nanocellulose samples [21]. They successfully report the production of nanosized droplets for CNC and TEMPO oxidized CNF using HP-homogenizer.…”

A pH-responsive Pickering Nanoemulsion for specified spatial delivery of Immune Checkpoint Inhibitor and Chemotherapy agent to Tumors

“…Pickering emulsions are stabilized by colloidal particles instead of conventional surfactants 33 , 34 . When the droplet diameter is in the nano range, the emulsions are referred to as Pickering nanoemulsion 35 , 36 . By sequential high-speed shearing and ultrasonic treatment, our laboratory successfully obtained PNE previously using nanogels 25 .…”

Engineered Multilayer Microcapsules Based on Polysaccharides Nanomaterials

“…Nanocrystals of smaller size are more convenient because a more dense organization on the polymer surface is created, while longer CNC formed an interconnected network [ 149 ]. Larger cellulose nanofibers resulted to larger structures with less surface coverage, connected by a strong interparticle network [ 150 , 151 ]. A better overview of the size range and of the structures of the resulting particles is shown in Figure 5 .…”