The project A3 focuses on microgels that are able to change their charge as function of pH (and temperature). We synthesize new microgels, which have a defined localization of charged groups inside the microgels and different architectures (random, core-shell, janus-like, and hollow), and investigate the swelling and collapse of the microgels with possible shape variations as function of different external stimuli. In addition we study the interaction of these microgels with polyelectrolytes. We determine the composition of the microgel-polyelectrolyte complexes as well as their structure and sensitivity to pH, salt concentration and temperature. We will introduce hollow microgels as new structural motif and investigate the uptake and release of charged species by the hollow microgels. The project combines two approaches: experiments (focusing on scattering techniques) and computer simulations.