Pathways and challenges towards a complete characterization of microgels

Due to their controlled size, sensitivity to external stimuli, and ease-of-use, microgel colloids are unique building blocks for soft materials made by crosslinking polymers on the micrometer scale. Despite the plethora of work published, many questions about their internal structure, interactions, and phase behavior are still open. The reasons for this lack of understanding are the challenges arising from the small size of the microgel particles, complex pairwise interactions, and their solvent permeability. Here we describe pathways toward a complete understanding of microgel colloids based on recent experimental advances in nanoscale characterization, such as super-resolution microscopy, scattering methods, and modeling. Despite their widespread use, many fundamental questions about the internal structure of microgels are still open. Here the authors describe several pathways toward a complete understanding of microgel colloids based on recent experimental advances in nanoscale characterization.