Tuning interfacial viscoelasticity of catechol-functionalized alginate by pH-responsive covalent network for stabilizing high internal phase pickering emulsions

Abstract

Polysaccharide-based soft particles have wide applications in preparing high phase Pickering emulsions (HIPPEs) because of their adjustable interfacial properties, which can advance the stability of HIPPEs by strengthening their interfacial viscoelasticity. Nevertheless, there is limited research on the interfacial viscoelasticity of soft particles regarding the stability of HIPPEs. We synthesized Alg-CA soft particles by the Ugi reaction, featuring catechol functionality and amphiphilic alginate. These particles can self-assemble under pH stimulation, resulting in a network structure that impacts the interfacial viscoelasticity of HIPPEs. We investigated the relationship between self-assembled microstructure and interfacial viscoelasticity using transmission electron microscopy (TEM) and rheometry. The study indicates that the Alg-CA solution produced a compact network structure at a pH level of 3, leading to the formation of highly stable HIPPEs (with a viscosity of approximately 1000 Pa·s). Additionally, by utilizing emulsion templates, 3D network aerogels with pH-sensitive, consistent microstructures may be developed, which presents a promising approach for designing and producing aerogels with distinct microporous architectures.