Polymeric Microgels: Insights from Light Scattering, Electron Microscopy, and Optical Super‐Resolution Techniques

Employing micro- and nanogels in a controlled way for various studies and applications requires acquiring a detailed picture about their structure and in-situ behavior, particularly when the microgels are also stimuli-responsive or are hybrid microgels composed of two or several different components. Core-shell microgel structures are common. Moreover, microgels can be decorated with nanoparticles or DNAs for added functionality or when using the microgel as a carrier. The properties of microgels are often governed by the interface, which can have a quite different density compared to the bulk. Adding charges can change the microgel morphology substantially. There is no single method that can address all the challenges that arise when characterizing such complex mesoscale structures with the necessary nanoscale or even molecular resolution. A number of strategies have been reported in the field, and often a combination of methods can help to gain a better understanding of the microgel morphology and function. In the present section, we will introduce the most common methods and showcase recent implementations of these techniques. We will also discuss their limitations and the pitfalls that exist if these methods are not applied correctly or if the data is not analyzed with caution.