Stimuli-Responsive Polymer Architectures

Prof. Dr. Markus Gallei, Saarland University, Saarbrücken

Over the last decade, stimuli-responsive polymers have attracted considerable attention for a range of important applications. Such polymers are capable of changing their conformation and solubility, or they can even break or form covalent bonds upon a change of temperature or pH value, upon light irradiation, by using electrochemical stimuli, or by the presence of an electrical or magnetic field, or by combinations thereof. The presentation will focus on two polymer classes, which contain at least one selectively addressable segment, either chemically or physically: (i) the microphase separation of block copolymers is exploited in the bulk state but also using the non-solvent induced phase separation (NIPS) process for the preparation of nanoporous and switchable structures to gain access to flexible integral asymmetric membranes. The selective isoporous layer can be altered by external triggers, such as redox chemistry, pH value, or temperature. This switching capability can be utilized for an efficient and fully reversible control over the water flux, thereby facilitating the separation of components. (ii) Functional opal films prepared by using the so-called melt-shear organization technique based on core-shell particles will be highlighted and discussed in more detail. Within polymeric opals, external triggers can lead to fast and reversible changes in their intriguing optical properties, which could be easily processed into films or 3D-printed into complex objects . A major benefit of self-assembled polymeric materials is their inexpensive and convenient preparation, giving a good optical performance. The talk will provide recent advances in the rational design of functional (porous) switchable materials with hierarchical architectures. The preparation strategies presented herein will pave the way for numerous applications in sensing and smart membrane technologies.