A Multi-Step model to predict the size of stabilized oil droplets in pickering emulsions containing janus and non-janus nanoparticles

Abstract

In this study, a multi-step model is proposed to predict the average size of stabilized oil droplets in Pickering emulsions considering the characteristics, participation ratio, three-phase contact angle, and aggregation/agglomeration of nanostabilizers. As the first step, a novel model is proposed to define the size and volume fraction of the aggregated/agglomerated domains based on the thermal conduction coefficient of water/nanostabilizer suspensions. Next, the average radius of the stabilized oil droplets is predicted using another designed model considering the content of involved nanostabilizers and their penetration depth inside the oil phase. Three different OX-50 silica nanoparticles (bare, homogenously modified (HM) and Janus) are used as stabilizers in Pickering emulsions. Janus nanoparticles are synthesized using a one-step desymmetrization process and the characteristics of the products are verified based on their behavior in the water/chloroform dual-phase system and FTIR test results. The results of the multi-step model are compared to the actual average radius of the stabilized oil droplets defined using the light-microscopy and FE-SEM tests. It was found that the proposed model is acceptably accurate in predicting the average size of the oil droplets in the systems containing bare and HM nanoparticles however, the unique behavior of Janus nanoparticles causes an overprediction.