Research Focus



Active polymer gels are soft materials with adaptive action. Their function is based on non-covalent binding in the gel network, either in a sense of transient chain connectivity or in a sense of delicate interactions of the chains with their environment. Both modes of action can serve in various advanced applications in which a gel specimen serves to adapt its viscoelasticity and/or permeability in response to external parameters. However, to make this all truly useful, it is necessary to understand the mutual interplay between (nano)structure, dynamics, and properties of these fascinating materials. This is what our research is focusing upon.





Research Areas


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Supramolecular Polymer Networks consist of polymer chains interlinked by non-covalent interactions. To rationally exploit their utility, it is necessary to understand the interplay between their structure, dynamics, and properties. We approach this goal by synthesizing toolboxes of polymers functionalized with different supramolecular crosslinkable motifs. These polymers form a variety of supramolecular networks that we study to correlate their macroscopic properties to their supramolecular equilibria and nm-scale structures.


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Heterogeneous Polymer Gelsexhibit pronounced spatial variation of their crosslinking density on nm-scales. We aim to understand both the origin and the impact of these inhomogeneities on the gel macroscopic mechanics, microscopic chain dynamics, and stimuli-sensitive volume phase transitions. For this purpose, we use controlled precursor-polymer gelation in droplet-based microfluidics along with rheology, microscopy, and light-, neutron-, and x-ray scattering.


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Smart Microgel Capsules
are micrometer-sized soft polymer particles that can be actuated by external stimulation, either by selective swelling and deswelling or by selective crosslinking and decrosslinking. We use droplet-based microfluidics to fabricate such particles to host complex additives. In particular, we focus on encapsulating living cells into these microgels to embed them within artificial extracellular matrixes with determined and tunable properties.



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Microgel Suspensions
are composed of soft and deformable particles that can be packed to high effective volume fractions. Such packing transforms a suspension of loose microgels to an arrested state with properties similar to that of macroscopic polymer gels. This effect provides a path to mimic polymer gels with determined heterogeneous composition. We follow this approach and prepare microgel packings that comprise both densely and loosely crosslinked microgel building blocks, which we then probe by micro- and macrorheology.



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Droplet-Based Microfluidics is the fine-art of flowing immiscible fluids in small channels to form droplets with controlled monodisperse sub-mm sizes. These droplets are useful for two areas of application. In one area of application, the droplets serve as templates to form microparticles, including soft polymer microgels. In another area of application, the droplets can serve as picoliter compartments, which we use in conjunction with small-angle x-ray scattering.




Research Contacts


Recent Collaborations

A. Fery
, IPF Dresden
Core–Shell Microgels with Switchable Elasticity
ACS Appl. Mater. Interfaces 2016, 8, 16317–16327.

W. Richtering, RWTH Aachen University
Dynamics in Composite Gels, Microgel Packings, and Core–Shell Microgels
J. Am. Chem. Soc. 2012, 134, 15963–15969.
J. Colloid Interface Sci. 2014, 431, 204–208.
Colloid Polym. Sci. 2017, 295, 1371–1381.

R. von Klitzing, TU Darmstadt
Mechanics of Inhomogeneous Polymer Gels
ACS Macro Lett. 2015, 4, 698–703.

K. Saalwächter, Halle University
Microgel Phase Transitions
Macromol. Chem. Phys. 2014, 215, 1116–1133.
J. Polym. Sci. B: Polym. Phys. 2015, 53, 1112–1122.

D. A. Weitz, Harvard University; R. Haag, FU Berlin
Cell-Laden Microgels

J. Am. Chem. Soc. 2012, 134, 4983−4989.
Angew. Chem. Int. Ed. 2013, 52, 13538–13543.
Adv. Healthcare Mater. 2015, 4, 1841–1848.

B. D. Olsen, Massachusetts Institute of Technology
Microscopic Chain Dynamics in Supramolecular Polymer-Network Gels
Macromolecules 2016, 49, 5599–5608.


Recent and Current Industry Projects

Siemens AG
, Berlin, Germany
Polymer-Based Engine Insulators

Procter & Gamble Germany GmbH & Co Operations oHG, Schwalbach, Germany
Polyelectrolyte Superabsorbers

BASF SE, Ludwigshafen, Germany
Microgel Additives for Care Products