Smart Microgel-Based Membranes for Enhanced Catalysis and Electrochemical Cells - From Understanding Structure to Custom-Designed Devices.

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Catalysis, energy storage and conversion are at present of paramount societal relevance. Unfortunately, electrochemical potentials are basically known since one century and cannot be significantly enhanced. Therefore, the possibility to increase storage capacity and current flux is only possible by minimizing cells. This involves the development of smart membranes having thicknesses in the nanoscale. Moreover, such membranes should have smart properties allowing to control ion flux by external stimuli and having intrinsic safety properties e.g. self regulation of ion flux (current) upon overheating. Similar aspects apply to catalysis by nanoparticles (NP), which is highly effective due to NPs great specific surface. Anyhow, activity of NPs is difficult to control and the bare particles are difficult to separate from the product. In both contexts of smart membranes, the German partner has recently developed a way to cross-link microgels into macroscopic free-standing membranes which were found to exhibit resistance controlled by temperature. The microgels are made by copolymerisation of classical acrylamides and of photo- or electron beam-crosslinkable comonomers. However, at present many details of the local structure of these microgels are unknown, in particular how the comonomers (resp. nanoparticles) are spatially distributed, and how their distribution influences mechanical, resistive, or catalytic membrane properties. In a previous joint French-German project the Montpellier and the Bielefeld group have developed the tools which allow the determination of the structure of such copolymer microgels in detail by neutron scattering methods, based on isotopic substitution and computer simulations. The present project aims at exploiting and extending this knowledge to establish structure-property relations for smart microgel membranes. We will apply combinations of scattering, simulations, and imaging methods to specially-designed microgel particles containing different comonomers and catalytically-active nanoparticles in view of the formation of freestanding and crosslinked films. Then a similar analysis will be performed after film formation, and correlated with transport (resp. catalytic) properties. Based on this the partners will construct either first smart electrochemical devices, or proof-of-principle flow-through reactors with controllable catalytic activity.