The controlled synthesis of hierarchically functionalized core/multishell particles is highly desirable for applications in medicine, catalysis, and separation. Here, we describe the synthesis of hierarchically structured metal-organic framework multishells around magnetic core particles (magMOFs) via layer-by-layer (LbL) synthesis. The LbL deposition enables the design of multishell systems, where each MOF shell can be modified to install different functions. Here, we used this approach to create controlled release capsules, in which the inner shell serves as a reservoir and the outer shell serves as a membrane after postsynthetic conversion of the MOF structure to a polymer network. These capsules enable the controlled release of loaded dye molecules, depending on the surrounding media.
Easy come, easy go: the first molecular SO(2) complexes of the lanthanides (Ln=Sm, Eu) have been prepared. The compounds can reversibly coordinate gaseous SO(2). Concomitant with the addition and removal of SO(2), the color of the complexes changes reversibly. The structures of the SO(2) compounds could be confirmed in solution and in the solid state.
The increasing demand for materials with well-defined microstructure, accompanied by the advancing miniaturization of devices is the reason for a growing interest in physically motivated, dislocation-based continuum theories of plasticity. In recent years, various advanced continuum theories have been introduced, which are able to described the motion of straight and curved dislocation lines. The focus of this paper is the question of how to include fundamental properties of discrete dislocations during their motion and interaction in a Continuum Dislocation Dynamics (CDD) theory. In our CDD model, we obtain elastic interaction stresses for the bundles of dislocations by a mean-field stress, which represents long range stress components, and a short range corrective stress component, which represents the gradients of the local dislocation density. The attracting and repelling behavior of bundles of straight dislocations of the same and opposite sign are analyzed. Furthermore, considering different dislocation pileup systems, we show that the CDD formulation can solve various fundamental problems of micro plasticity. To obtain a mesh size independent formulation (which is a prerequisite for further application of the theory to more complex situations) we propose a discretization dependent scaling of the short range interaction stress. CDD results are compared to analytical solutions and benchmark data obtained from discrete dislocation simulations.
The ability to control the structure and topology of polymer networks, both on macroscopic and molecular levels, is crucial for optimizing their performance.Here we describe a novel type of network polymer, which is synthesized via conversion of a highly ordered metal−organic framework (MOF) template into a polymer gel. The synthesis is performed using light-induced and metal-free thiol−ene click chemistry. The use of light-triggered reactions in combination with photomasks or other photopatterning techniques allows the reaction to be locally confined and thereby structuring the network polymer on a macroscopic level. The potential to vary and exactly adjust the parameters within the polymer network (including exact network topology on the nanometer scale as well as the macroscopic morphology) combined with the ability to further functionalize their surfaces or incorporate guest molecules allows their targeted design for potential applications in catalysis and optoelectronics as well as their use as a novel biomaterial.
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