Microgels at interfaces, from mickering emulsions to flat interfaces and back

Miguel Angel Fernandez-Rodriguez; Alberto Martín-Molina; Julia Maldonado-Valderrama

doi:10.1016/j.cis.2020.102350

Microgels at interfaces, from mickering emulsions to flat interfaces and back

Adv Colloid Interface Sci. 2021 Feb:288:102350. doi: 10.1016/j.cis.2020.102350. Epub 2020 Dec 21.

Authors

Miguel Angel Fernandez-Rodriguez¹, Alberto Martín-Molina², Julia Maldonado-Valderrama³

Affiliations

¹ Department of Applied Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain.
² Department of Applied Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain; Institute Carlos I for Theoretical and Computational Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain.
³ Department of Applied Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain; Excellence Unit "ModellingNature" (MNat), , University of Granada, Spain. Electronic address: julia@ugr.es.

PMID: 33418470
DOI: 10.1016/j.cis.2020.102350

Abstract

In this review, we cover the topic of p(NIPAM) based microgels at interfaces, revisiting classical studies in light of the newest ones. In particular, we focus on their use as emulsifiers in the so-called mickering emulsions, i.e. Pickering emulsion stabilized by soft particles. Given the complexity of the experimental characterization and simulation of these soft particles at interfaces, the review is structured in progressive complexity levels, until we reach the highly interesting and promising responsiveness to stimuli of mickering emulsions. We start from the lowest level of complexity, the current understanding of the behavior of single microgels confined at a flat interface. Then, we discuss their collective behavior upon crowding, their responsiveness at interfaces, and their macroscopic properties as microgel films. Once we have the necessary characterization tools, we proceed to discuss the complex and convoluted picture of responsive mickering emulsions. The way is rough, with current controversial and contradicting studies, but it holds promising results as well. We state open questions worth of being tackled by the Soft Matter community, and we conclude that it is worth the trouble of continuing after the master theory of microgel interfacial activity, as it will pave the way to widely adopt responsive mickering emulsions as the worthy Pickering emulsion successors.

Keywords: Interfacial rheology; Interfacial tension; Mickering emulsions; Microgels; Responsiveness; Visco-elasticity.

Publication types

Review