Topological evolution of complex polymer nanostructures as templates for hybrid material

Andrea Steinhaus, University of Duisburg-Essen, Duisburg , Germany
Stefanie Tjaberings, University of Duisburg-Essen, Duisburg , Germany
André H. Gröschel, University of Duisburg-Essen, Duisburg, Germany

Block copolymer nanoparticles with unusual inner structure and complex surface are currently researched as non-trivial soft matter due to their unique physical properties and their potential as templates for inorganic compounds.[1] Introducing noble metals (e.g. platinum, gold, silver) into the inner polymer phase offers the possibility to create metal nano-replicas, whose unique shape could be beneficial for drug delivery whereupon their high surface area enhances catalytic performance.[2]

We here report on the versatile synthesis of a range of new Janus nanostructures with diverse topology, e.g. rings, grates, perforated disks, and filled disks, that carry two strictly separated polymer brushes of different chemistry. We find that properly designed polystyrene-b-polybutadiene-b-polymethylmethacrylate (SBM) triblock terpolymers are able to self-assemble into multicompartment microparticles with novel lamella morphologies when exposed to outer confinement of nanoemulsion droplets, where domains are deflected at the curved interface.[3] Subsequent cross-linking of the polybutadiene (PB) phase fixes the inner geometry to generate symmetric Janus nanostructures after re-dispersion of the multicompartment microparticles in organic solvents. The blending of PB homopolymer into the microparticle leads to morphological transitions within the PB phase, which results in unusual anisotropic grates, perforated disks as well as transition structures between these two motifs. The transition is made by distinct topological evolutionary steps in which polymer chains pack according to certain rules. Using these nanostructures as template, it is possible to imbed platinum into the PB domain still surrounded by hydrophobic polystyrene (PS) and polymethyl methacrylate (PMMA) corona. The presented process opens the way to novel polymeric nanoparticles and thus gives the opportunity to systematically test the influence on the nanoparticles’ shape, inner structure and surface in the field of drug delivery and catalysis.[2]

(1) Gröschel, A. H.; Müller, A. H. E. Nanoscale 2015, 7, 11841-11876.
(2) Werner, J. G.; Wiesner U. Energy Environ. Sci., 2018, 11, 1261-1270.
(3) Steinhaus, A.; Chakroun, R.; Nghiem, T.-L.; Müllner, M.; Gröschel, A. H. submitted.

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