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

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.