@article{SchueringsNevskyiEliaschetal.2016, author = {Sch{\"u}rings, Marco-Philipp and Nevskyi, Oleksii and Eliasch, Kamill and Michel, Ann-Katrin and Liu, Bing and Pich, Andrij and B{\"o}ker, Alexander and von Plessen, Gero and W{\"o}ll, Dominik}, title = {Diffusive Motion of Linear Microgel Assemblies in Solution}, series = {Polymers}, volume = {8}, journal = {Polymers}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym8120413}, pages = {14}, year = {2016}, abstract = {Due to the ability of microgels to rapidly contract and expand in response to external stimuli, assemblies of interconnected microgels are promising for actuation applications, e.g., as contracting fibers for artificial muscles. Among the properties determining the suitability of microgel assemblies for actuation are mechanical parameters such as bending stiffness and mobility. Here, we study the properties of linear, one-dimensional chains of poly(N-vinylcaprolactam) microgels dispersed in water. They were fabricated by utilizing wrinkled surfaces as templates and UV-cross-linking the microgels. We image the shapes of the chains on surfaces and in solution using atomic force microscopy (AFM) and fluorescence microscopy, respectively. In solution, the chains are observed to execute translational and rotational diffusive motions. Evaluation of the motions yields translational and rotational diffusion coefficients and, from the translational diffusion coefficient, the chain mobility. The microgel chains show no perceptible bending, which yields a lower limit on their bending stiffness.}, language = {en} } @phdthesis{Leiendecker2016, author = {Leiendecker, Mai-Thi}, title = {Physikalische Hydrogele auf Polyurethan-Basis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103917}, school = {Universit{\"a}t Potsdam}, pages = {109}, year = {2016}, abstract = {Physical hydrogels have gained recent attention as cell substrates, since viscoelasticity or stress relaxation is a powerful parameter in mechanotransduction, which has long been neglected. We designed multi-functional polyurethanes to form physical hydrogels via a unique tunable gelation mechanism. The anionic polyurethanes spontaneously form aggregates in water that are kept in a soluble state through electrostatic repulsion. Fast subsequent gelation can be triggered by charge shielding which allows the aggregation and network building to proceed. This can be induced by adding either acids or salts, resulting in acidic (pH 4-5) or pH-neutral hydrogels, respectively. Whereas conventional polyurethane-based hydrogels are commonly prepared from toxic isocyanate precursors, the physical hydrogelation mechanism described here does not involve chemically reactive species which is ideal for in situ applications in sensitive environments. Both stiffness and stress relaxation can be tuned independently over a broad range and the gels exhibit excellent stress recovery behavior.}, language = {de} }