SFB 1073 Atomic scale control of energy conversion

Project A03

A03 Thermal transport in polymeric nanostructures
Using simulation and experiment, we will investigate the energy transport (i) across the internal interfaces in nanostructured composite materials of amorphous block copolymers, (ii) at the interface between polymers and inorganic nanoparticles and, (iii) at the free surface of polymer materials after mechanical excitation. Energy transport will be controlled by molecular conformations at interfaces and surfaces, by the compressibility of the material, by embedding nanoparticles into specific polymer domains, as well as by changing the orientation and size of the microphase-separated domains through energy input in form of UV light. This may open up pathways to materials with switchable thermal conductivity.


A03 Thermischer Transport in Polymernanostrukturen
Mittels Simulation und Experiment werden wir den Energietransport (i) durch die internen Grenzflächen von Blockcopolymermaterialien, (ii) an der Grenzfläche zwischen Polymer und anorganischen Nanopartikeln, und (iii) an der freien Oberfläche des Polymermaterials nach mechanischer Anregung untersuchen. Der Energietransport wird dabei sowohl durch die Polymerkonformationen an den Grenz- und Oberflächen, die Kompressibilität der Materialien, durch die Einbettung von Nanopartikeln in ausgewählte Domänen, als auch der Orientierungs- und Größenänderung der Domänen mittels UV-Licht gesteuert. Dies ermöglicht, Materialien mit schaltbaren Wärmeleitungseigenschaften zu erhalten.



A03_Grafik

Here, the light-induced self-assembly of gold nanoparticles can be seen. A methacrylate type monomer with an azobenzene sidechain was polymerized in a reversible addition–fragmentation chain transfer (RAFT) polymerization. The resulting light responsive polymer was grafted to gold nanoparticles via the RAFT group. UV-light induced trans to cis isomerization of the azobenzene moieties triggers the aggregation of the polymer–gold hybrid particles in toluene dispersion. The thermally induced cis to trans relaxation was found to be significantly slower than for small molecules at gold surfaces. The density of primary gold particles within the self-assembled aggregates can be tuned by varying the molar mass of the grafted polymer.