Synthesis of polymeric Janus nanoparticles by co-precipitation in a rotating packed bed to stabilize carvacrol encapsulated Pickering emulsions

Practical application of carvacrol in different fields including foods and biopesticides has been limited due to its instability and water insolubility. In this work, carvacrol encapsulated Pickering emulsion is developed by using polymeric Janus nanoparticles as the stabilizer. To achieve this, dumbbell-shaped polymeric nanoparticles composed of two spheres of shellac and polylactic acid (PLA) are firstly prepared via co-precipitation in a rotating packed bed reactor, followed by grafting of chitooligosaccharides (COS) onto shellac to synthesis amphiphilic Janus nanoparticles (PLA/shellac-COS). Pickering emulsions with typical oil-in-water, bi-continuous structure and water-in-oil characteristics are produced by configuring carvacrol emulsions with different oil-to-water ratios. The stability of emulsions with 5% carvacrol content stabilized by 0.5% PLA/shellac-COS nanoparticles were more stable when compared to those prepared by shellac nanoparticles and PLA/shellac nanoparticles. After stored for one month, the carvacrol encapsulated Pickering emulsions maintained a high zeta potential of −43.8 mV, with no significant changes in particle size. These preliminary studies illustrated that polymeric Janus nanoparticles synthesized by co-precipitation in a rotating packed bed are promising particles for Pickering emulsions and related work in the future.