Enhancing interfacial elasticity via supramolecular microgel assembly for improved Pickering emulsions stability

Abstract

We propose a new method to improve the interfacial elasticity of microgel-stabilised Pickering emulsions (PEs) by introducing supramolecular host-guest interactions to promote clustering among microgel particles. To this aim, microgels based on poly(N-isopropylacrylamide) (pNIPAM) are modified with 1-benzyl-3-vinylimidazolium bromide (BVI) to create pNIPAM-co-BVI microgels (MG). Cucurbit[8]uril (CB[8]) are introduced to form supramolecular BVI/CB[8] host-guest complexes. The introduction of CB[8] affects microgel spatial distribution at the interface of Pickering droplets, promoting the formation of monolayers of microgel clusters. These structures alter the interfacial viscoelasticity of the microgel monolayers, enhancing the resistance of (MG+CB[8])-stabilised interfaces to lateral and dilational deformations. PEs stabilised by microgels with the presence of CB[8] host-guest interactions exhibit improved stability over time. These results show the possibility of tuning the interfacial properties of microgel-laden interfaces by introducing supramolecular ternary complexes that can solely alter the interparticle interactions among microgels without significantly changing their morphology and deformability at the interface, thus providing a new route for improved emulsion stabilisation.