Compartmentalization in soft matter is important for segregating and coordinating chemical reactions, sequestering (re)active components, and integrating multifunctionality. Advances depend crucially on quantitative 3D visualization in situ with high spatiotemporal resolution. Here, we show the direct visualization of different compartments within adaptive microgels using a combination of in situ electron and super-resolved fluorescence microscopy. We unravel new levels of structural details and address the challenge of reconstructing 3D information from 2D projections for nonuniform soft matter as opposed to monodisperse proteins. Moreover, we visualize the thermally induced shrinkage of responsive core-shell microgels live in water. This strategy opens doors for systematic in situ studies of soft matter systems and their application as smart materials.

We report on the swelling of a polymeric network in doubly thermoresponsive microgels. Silica-core double-shell and hollow double-shell microgels made of an inner poly(N-isopropylmethacrylamide) and an outer poly(N-isopropylacrylamide) shell are studied by exploiting the distinct temperature sensitivities of the polymers. The swelling states of the two shells can be tuned by temperature changes enabling three different swelling states: above, below, and between the distinct volume phase transition temperatures of the two polymers. This enables to investigate the effect of different constraints on the swelling of the inner network. Small-angle neutron scattering with contrast variation in combination with computer simulation discloses how the expansion of the inner shell depends on the material and swelling state of its constraints. In the presence of the stiff core, the microgels show a considerable interpenetration of the polymeric shells: the inner network expands into the outer deswollen shell. This interpenetration vanishes when the outer network is swollen. Furthermore, as predicted by our computer simulations, an appropriate choice of cross-linking density enables the generation of hollow double-shell nanocapsules. Here, the inner shell undergoes a push−pull ef fect. At high temperature, the collapsed outer shell pushes the swollen inner network into the cavity. At lower temperature, the swelling of the outer network contrary pulls the inner shell back toward the external periphery.

With the help of a technique combining in situ electrical impedance spectroscopy and DRIFT spectroscopy, we observed directly the formation of ammonium ion (NH 4 + ) intermediates resulting from the interaction of NO and NH 3 on Fe-ZSM-5 catalysts for selective catalytic reduction by NH 3 (NH 3 −SCR). The formed NH 4 + intermediates, indicating the activation of NO in the presence of adsorbed NH 3 , were found to be strongly related to the NH 3 −SCR activity of Fe-ZSM-5 catalysts at low temperatures. These findings, which are not easily achievable by conventional methods, provide new and important perspectives to understand mechanistically the NH 3 −SCR reaction over Fe-zeolite catalysts.

Advancing biomedicine by tunable e-transfer into/from microgels.