pH‐ and Redox‐Responsive Pickering Emulsions Based on Cellulose Nanocrystal Surfactants

Abstract

Nanoparticle surfactants (NPSs), formed by using dynamic interactions between nanoparticles and complementary ligands at the liquid-liquid interface, have emerged as "smart emulsifiers" with attributes of high emulsification efficiency, long-term stability, and on-demand emulsification/demulsification capabilities. However, only pH-responsiveness can be adopted for the assembly of reported NPSs formed by electrostatic interactions. Here, we propose an alternative design strategy, by taking advantage of the ferrocenium (Fc + ) sulfate ion pair, to develop a new type of cellulose nanocrystal (CNC) surfactant. The Fc + groups are sensitive to pH, redox reagents and voltage, imparting the CNC surfactants and derived Pickering emulsions with multi-stimuli-responsiveness, and showing promising applications in controllable delivery, release, and biphasic biocatalysis.

Controllable Regulation of Diesel Oil-in-Water Pickering Emulsion Stability by Multiresponsive Recyclable Magnetic Polymer Brush Microvessels

“…The surface carboxyl groups of MNPDNML microspheres were deprotonated, which endowed the microspheres with amphiphilicity at pH 10. It facilitated the assembly of microspheres at the water–oil interface, which greatly reduced the interfacial tension . However, as pH increased to 11, the degree of carboxyl deprotonation increased, which resulted in enhanced hydrophilicity of the microspheres to inhibit the interfacial activity.…”

Pickering emulsion-derived nano/microreactors for unconventional interfacial catalysis: state-of-the-art advances and perspectives in green reactions

“…Catalysis plays a vital role in the chemical and power industries, as it is responsible for 95% of chemical engineering processes. 1–3 Catalysis has significantly contributed to reducing industrial energy consumption, which is still high, therefore there is a call for efforts to reduce it further. Sustainable chemistry and biphasic catalysis have been the goal of fine chemical synthesis and manufacturing over the last two decades.…”