Advanced polymeric solids containing nano- and micro-particles prepared via emulsion-based polymerization approaches. A review.

This review critically summarizes the latest contributions in the preparation of advanced nano/microparticle-contained polymers from emulsions. The nano- or micro-particles can be dispersed in the phase where the polymerization reaction takes place and, consequently, once the solid is formed, the particles are embedded in the final polymeric structure. This results in the formation of hybrid materials, which combine the unique properties of nano/micro-particles with the inherent properties of the polymers (which depend mainly on the selected monomers). In addition to this, some nano- and micro-particles can be used as solid stabilizers in emulsions. This kind of emulsions, called 'Pickering emulsions', presents some additional advantages over those prepared with conventional surfactants (e.g., non-ionic polymers) such as higher emulsion stability. In this way, the nano/micro-particles fulfill a double mission. On the one hand, they are responsible for forming and stabilizing the emulsion. On the other, they are part of the final solid, obtaining polymeric materials with new functionalities. In this context, this review aims to describe the most innovative strategies for the incorporation of nano- and micro-particles in polymers through the direct addition of them to the emulsion in which the polymerization is carried out. Also, the effect of the addition of these nano/micro-particles in the emulsions (e.g., size of droplets, type of emulsion and stability), the type of solids obtained (e.g., monolithic polymers or individual particles), morphology (e.g., open- or closed-cell polymers) and functionality of the final solid will be also commented on.