Ph.D candidate, University of Alberta
Instead of using chemical surfactants, wood resource is value-added and made as emulsion stabilizer
People in recent years are more and more aware of the commercial surfactants in emulsion products, especially in cosmetic/body care products, food, and pharmaceutical formulations (annual consumption reaching 2.6 million tons by 2017, Global Industry Analysts, Inc (GIA)). Some commercial surfactants, when employed as emulsifier in industry, need to be used at very high dosage, or even several emulsifiers combine at high dosage to obtain good emulsions. Recently, scientists found that the increased consumption of emulsifiers, such as polysorbate 80, could be a trigger of Crohn’s disease (CD) by increasing bacterial translocation. The abuse or overuse of commercial surfactants could be severe health/environment-issue when accumulated in human body or ecological system. Pickering emulsions are the emulsions stabilized by solid colloids, instead of commercial chemical surfactants in traditional emulsion products. Recent researches find Pickering emulsions have some distinctive benefits in terms of good biocompatibility, surfactant-free concept, and good stability at low dosage of stabilizer. therefore, Pickering emulsion shows a potential pathway to solve the problems of traditional emulsions. Cellulose is the most abundant biomass on the earth with an estimated annual production of ~1.5 × 1012 tons. Especially wood-based cellulose, with a dominant status in Canada, has received much attention due to its renewability, biodegradability, and biocompatibility. In this research, we employ cellulose nanocrystals as a robust stabilizer to stabilize Pickering emulsions. This research opens an avenue for cellulose materials as new interfacial materials, which will find applications in personal care, cosmetic and pharmaceutic industries.
Abstract: Cellulose nanocrystals are hydrophilic nanomaterials, which limits their applications as interfacial compounds. Herein, we propose using modified wood-based cellulose nanocrystals as Pickering emulsion stabilizer. Wood cellulose was consecutively oxidized and modified with phenyltrimethylammonium chloride to create hydrophobic domains comprised of phenyl groups. These modified oxidized cellulose nanocrystals (m-O-CNCs) were homogeneous/electrostatically stable in water and they can stabilize O/W Pickering emulsions. The dispersed phase volume fraction (DPVF) of the Pickering emulsion was 0.7 at around 1.5 g/L, whereas the tween-20 control needed a 13-fold greater concentration to have a similar DPVR. In addition, these m-O-CNC stabilized Pickering emulsions also showed good mechanical and thermal stability against centrifugation and heat, as well as size controllability. In terms of stability, size controllability, surfactant-free status, these m-O-CNCs possess superior and enhanced emulsifying properties. Future research for these new interfacial materials have potential in applications, for personal care, cosmetic and pharmaceutic industries.
Pub.: 14 Apr '17, Pinned: 28 Jun '17