Amphiphilic Janus nanoparticles with controlled composition and wettability for pickering emulsion with controllable movement and release

Abstract

Pickering emulsions represent an important class of functional materials with great potentials in field of sustainability and health, such as controlled drug release or catalysis. However, the limited tunability of the amphiphilicity and implementation of multiple components into Pickering emulsion are still challenges for reliable dynamic control. Here, a strategy to obtain a triphasic amphiphilic PS/Fe3O4@SiO2 Janus nanoparticles (JNPs) by cladding Fe3O4 NPs inside biphasic PS@SiO2 JNPs was proposed and validated. The sizes of the triphasic JNPs is in the range of 80–150 nm and water contact angle (θW) varies from 58.9° to 131.4°, indicating the wettability could be controlled at will. The formed JNPs are assembled at the oil-water interface to stabilize water-in-oil (W/O) and oil-in-water (O/W) emulsion droplets. The stabilized emulsion droplets exhibit excellent thermodynamic stability which is evidenced by the droplet viability of 50 %-80 % after 6 months or excellent salt and temperature-resistance. Moreover, the movement and demulsification are made possible with magnetic actuation of JNPs. Compared to without magnetism, the release of curcumin dissolved in water within W/O droplet was realized 70 % after 12 days, showing a promising application in controlled active material release. Taking advantage of controllable synthesis and the functionality, this proposed approach could be expanded for preparation of colloidal materials with complex chemical and incorporate additional functionality, suggesting opportunities for further applications in drug delivery, oil recovery fields, and other fields related Pickering emulsion.