Pickering emulsions: emulsion polymerization and systems stabilized with carbon allotropes or carbon-rich materials

Abstract

The use of Pickering emulsions (PEs) has recently expanded considerably in academia and industry due to their ease of preparation, remarkable stability, and versatility in applications. This review focuses on PEs stabilized by carbon-rich particles, such as functionalized graphene and graphene oxide (GO), among others. It includes general PE production and applications along with the stabilization of emulsions in which an emulsion polymerization occurs to generate a polymer that plays a key role in the final application. Novel aspects of this study compared to others consist of its focus on carbon-rich stabilizers and its inclusion of emulsion polymerization applications. The key factor to obtain a stable PE with these materials is to guarantee that they exhibit an amphiphilic nature (which is tunable in many cases) to stabilize the emulsion. The majority of the applications in recent literature use GO as a PE stabilizer due to its inherent amphiphilicity and versatility for further chemical modification. The most significant challenge for final applications is the scaling up of the production process of GO or other carbon-based materials as stabilizers so that they can perform reproducibly as PE stabilizers, as these processes are subject to significant variability. Future research will diversify and consolidate applications, focusing more on the practical implementation of these developments involving aspects such as scaling up, efficiency, and recyclability.