Multi-responsive Pickering emulsifiers: a comprehensive study on the emulsification–demulsification behavior of modified chitosan-coated Fe3O4 nanocomposites

The surface characteristics of stimuli-responsive Pickering emulsifiers can be modified by external environmental triggers, making them highly versatile in various applications. In this study, we report three novel organic–inorganic composite structure emulsifiers. These emulsifiers were designed with a core of magnetic Fe3O4 particles, surrounded by a protective silica layer, and coated on the exterior with three distinct types of modified chitosan (CS). Experimental results demonstrate that these emulsifiers can stabilize emulsion systems consisting of liquid paraffin and deionized water at a concentration of 0.5 wt%. The unique properties of the modified CS coatings allowed for the controlled demulsification of two types of emulsions by adjusting the proton concentration. Additionally, these emulsifiers exhibited magnetic-responsive demulsification under the control of an external magnetic field. The findings of this study provide valuable insights into the design and construction of multi-responsive chitosan-based magnetic Pickering emulsifiers with controllable properties.