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- ItemMacroscopic Self-Evolution of Dynamic Hydrogels to Create Hollow Interiors(Weinheim : Wiley-VCH Verlag, 2020) Han, L.; Zheng, Y.; Luo, H.; Feng, J.; Engstler, R.; Xue, L.; Jing, G.; Deng, X.; del Campo, A.; Cui, J.A solid-to-hollow evolution in macroscopic structures is challenging in synthetic materials. A fundamentally new strategy is reported for guiding macroscopic, unidirectional shape evolution of materials without compromising the material's integrity. This strategy is based on the creation of a field with a “swelling pole” and a “shrinking pole” to drive polymers to disassemble, migrate, and resettle in the targeted region. This concept is demonstrated using dynamic hydrogels containing anchored acrylic ligands and hydrophobic long alkyl chains. Adding water molecules and ferric ions (Fe3+) to induce a swelling–shrinking field transforms the hydrogels from solid to hollow. The strategy is versatile in the generation of various closed hollow objects (for example, spheres, helix tubes, and cubes with different diameters) for different applications.
- ItemGradient flows for coupling order parameters and mechanics(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2022) Schmeller, Leonie; Peschka, DirkWe construct a formal gradient flow structure for phase-field evolution coupled to mechanics in Lagrangian coordinates, present common ways to couple the evolution and provide an incremental minimization strategy. While the usual presentation of continuum mechanics is intentionally very brief, the focus of this paper is on an extensible functional analytical framework and a discretization approach that preserves an appropriate variational structure as much as possible. As examples, we first present phase separation and swelling of gels and then the approach of stationary states of multiphase systems with surface tension and show the robustness of the general approach.