Biphasic control strategy of polymers and nanoparticles for viscous oil removal and molecular release: Synthesis, mechanism and applications

Abstract

Responsive Pickering emulsions are an excellent platform to control the interfacial properties of oil–water systems. However, the removal of viscous crude oil from oily waste by external stimuli is still a challenge. Here, a dual-stimuli supramolecular assembly of the polymer and silica particles (PS) was designed to achieve desirable control of oil–water interfaces for viscous oil removal and controlled molecular release. The β-cyclodextrin-based polymer was fabricated through the atom transfer radical polymerization (ATRP) method for the host molecules responsive to UV light and amine-modified silica particles for the guest molecules responsive to pH. Utilizing their responsive properties, the PS system was demonstrated in this study to significantly enhance the oil washing efficiency (from 18.3% to 74.2%). Moreover, as the acidic condition was replaced by CO2 injection, it was further enhanced from 74.2% to 88.5%, which is beneficial to greener remediation and production. The responsive PS assembly was also applied for dye release with a slower or faster release of methyl red by tuning the stimuli (pH & UV light). The molecular mechanism was revealed via the molecular dynamics (MD) simulation, which articulates the interaction and motion of the PS system under various stimulations. More importantly, this novel assembly of the cyclodextrin-based polymer and amine-modified silica particles affords a simple and efficient route to enhance the removal of viscous oil waste and precisely control the molecular release. The findings of the molecular self-assembly in this work offer unique opportunities to integrate functional polymers and particles into the liquid–liquid interface, opening an avenue for applications in Pickering emulsions.