Metal-organic framework (MOF) gel, an emerging subtype of MOF structure, is unique in formation and function; however, its evolutionary process remains elusive. Here, the evolution of a model gel-based MOF, UiO-66(Zr) gel, is explored by demonstrating its sequential sol-gel self-assembly and nonclassical gel-crystal transformation. The control of the sol-gel process enables the observation and characterization of structures in each assembly stage (phase-separation, polycondensation, and hindered-crystallization) and facilitates the preparation of hierarchical materials with giant mesopores. The gelation mechanism is tentatively attributed to the formation of zirconium oligomers. By further utilizing the pre-synthesized gel, the nonclassical gel-crystal transformation is achieved by the modulation in an unconventional manner, which sheds light on crystal intermediates and distinct crystallization motions (“growth and splitting” and “aggregation and fusion”). The overall sol-gel and gel-crystal evolutions of UiO-66(Zr) enrich self-assembly and crystallization domains, inspire the design of functional structures, and demand more in-depth research on the intermediates in the future. 相似文献
The characteristics of honeycomb plates composed of an upper and lower lamination are employed to create a novel single-sided bonded honeycomb plate (SBHP) design, and the compressive and flexural properties of these biomimetic integrated honeycomb plates are investigated. The results demonstrate that even during the fracturing of the honeycomb plates (honeycomb core), no abrupt compression paralysis occurs (which would cause the load to decrease rapidly); furthermore, our honeycomb plates exhibit superior compressive properties compared to biomimetic sandwich plates manufactured using Zhang’s needle-injection method. The interfacial bonding surface and bonding quality have no significant effect on the flexural stiffness but do affect the failure modes and flexural failure strength of the honeycomb plates. The ultimate failure of the biomimetic integrated honeycomb without a bonding layer between the panel–core layers is determined by the material strength itself; therefore, the honeycomb possesses good mechanical properties. This experimental study confirms, for the first time, the effectiveness of the biomimetic integrated honeycomb structure manufacturing method. 相似文献
By adopting polydopamine chemistry, a single‐step approach is introduced toward hierarchical surfaces with tunable surface wetting properties via adjusting the reaction temperature. After the hydrophobic surface decoration, the tunable superhydrophobicity of the surfaces is achieved. This tunability has been realized on a series of materials with different surface geometries, including silica nanospheres and microrods, silicon wafer, stainless steel mesh, and melamine‐formaldehyde sponge. These superhydrophobic mesh and sponge are ideal candidates for collecting various oils/organic solvents from water, because not only they exhibit high absorption/separation capacity, excellent selectivity, and extraordinary recyclability, but also they are highly chemically resistant, environmentally stable and mechanically durable. This whole procedure is straightforward, cost‐effective, green, and material‐ and surface geometry‐independent, more importantly, the obtained surface morphology is tunable, providing more opportunities to cater the demands from fundamental and practical fields. 相似文献
The subtle performance of a virus is closely related to its specific hierarchical structure, which is composed of a rigid shell and transverse, responsive, nanometer‐sized channels. Virus‐like structured colloids are of great interest for their potential applications, for example in drug delivery. Adequate knowledge of the structure and composition control of both colloids and mesoporous materials is significant in the design and synthesis of hierarchically structured colloids to mimic viruses. Some recent developments in the synthesis of composite colloids and mesoporous materials are summarized. Template synthesis is a major tool to control both the macroscopic morphology and microstructures of these composites, in which gel colloids and supramolecular structures from amphiphilic species are used as templates.
Studying binding interactions involving living cells requires a platform that carefully mimics the physiological parameters that govern these phenomena. Very often the amount of ligands that receptors can bind affect overall binding strength as is the case in cell adhesion. In addition, the physical environment can strongly influence these processes. This is exemplified by the effect of shear stress in catch‐bond‐mediated binding of bacteria. Traditional analysis techniques do not allow to probe these factors simultaneously. To this end, continuous ligand gradients in locked‐in supported lipid bilayers (SLBs) are prepared in a microfluidic device to control fluid flow. This platform allows for one‐pot characterization of cell surface binding events and 1) the effect of ligand density and 2) shear stress, simultaneously. The model interaction between the FimH receptor found on Escherichia coli and mannose found on the mammalian cell membrane is used to evaluate the platform. Using a single chip, specific E. coli ORN 178 adhesion (Kd of 0.9 × 10−21 m ), detachment and displacement are shown to depend on the mannose‐density and shear stress. For the first time, these effects are studied in a single chip device with high quality. This chip provides entry to further our understanding of other cell–cell interactions. 相似文献
Prof. Takuzo Aida is one of the most visible materials chemists thanks to his many creative contributions to the broad field of supramolecular chemistry. Over the past two decades he has ingeniously utilized self-assembly across scales and between various components to access a breathtaking variety of complex materials with fascinating properties. For example, the Aida Lab has pioneered conducting “bucky gel” by dispersing carbon nanotubes in ionic liquids as well as “aqua materials”, in which a tiny amount of additive renders water mechanically robust. From his personal insight he shares in this Interview, we can learn how his research evolved since his undergraduate studies. Moreover, he shares his vision on the importance of supramolecular polymers (Supra-Plastics) to realize a sustainable society. 相似文献
Preparation of real ladder polysiloxanes (LPSs), including both oxygen‐bridged ladder polysilsesquioxanes (LPSQs) and organo‐bridged ladder polysiloxanes (OLPSs), had been a great challenge to polymer chemists from 1960 until the successful synthesis of LPSs via the supramolecular architecture‐directed stepwise coupling polymerization (SCP) in the early 1980s. This opened up a new field of LPS‐based advanced materials. As key building blocks, LPSs are used to construct a variety of polysiloxanes with special steric configurations and functions, such as mesomorphic LPSs, tubular polysiloxanes (TPs), and pseudo‐sieve‐plate polysiloxanes (pseudo‐SPSs). With excellent temperature and radiation resistance, good solubility, and fine optical and mechanical properties, all these polysiloxanes demonstrate very promising prospects in the advanced materials realm. Here, the synthesis of well‐ordered LPSs is presented and features of fishbone‐like and rowboat‐like liquid crystalline polysiloxanes are discussed. Special emphasis is given to typical applications of LPSs, TPSs, and pseudo‐SPSs in the areas of liquid crystal displays, microelectronics packaging, and nonlinear optical materials. 相似文献
Achieving the full control over the production as well as processability of high‐quality graphene represents a major challenge with potential interest in the field of fabrication of multifunctional devices. The outstanding effort dedicated to tackle this challenge in the last decade revealed that certain organic molecules are capable of leveraging the exfoliation of graphite with different efficiencies. Here, a fundamental understanding on a straightforward supramolecular approach for producing homogenous dispersions of unfunctionalized and non‐oxidized graphene nanosheets in four different solvents is attained, namely N‐methyl‐2‐pyrrolidinone, N,N‐dimethylformamide, ortho‐dichlorobenzene, and 1,2,4‐trichlorobenzene. In particular, a comparative study on the liquid‐phase exfoliation of graphene in the presence of linear alkanes of different lengths terminated by a carboxylic‐acid head group is performed. These molecules act as graphene dispersion‐stabilizing agents during the exfoliation process. The efficiency of the exfoliation in terms of concentration of exfoliated graphene is found to be proportional to the length of the employed fatty acid. Importantly, a high percentage of single‐layer graphene flakes is revealed by high‐resolution transmission electron microscopy and Raman spectroscopy analyses. A simple yet effective thermodynamic model is developed to interpret the chain‐length dependence of the exfoliation yield. This approach relying on the synergistic effect of a ad‐hoc solvent and molecules to promote the exfoliation of graphene in liquid media represents a promising and modular strategy towards the rational design of improved dispersion‐stabilizing agents. 相似文献
Peptide self-assembly is a powerful tool to prepare functional materials at the nanoscale. Often, the resulting materials have high aspect-ratio, with intermolecular β-sheet formation underlying 1D fibrillar structures. Inspired by dynamic structures in nature, peptide self-assembly is increasingly moving toward stimuli-responsive designs wherein assembled structures are formed, altered, or dissipated in response to a specific cue. Here, a peptide bearing a prosthetic glucose-binding phenylboronic acid (PBA) is demonstrated to self-assemble into an uncommon nanocoil morphology. These nanocoils arise from antiparallel β-sheets, with molecules aligned parallel to the long axis of the coil. The binding of glucose to the PBA motif stabilizes and elongates the nanocoil, driving entanglement and gelation at physiological glucose levels. The glucose-dependent gelation of these materials is then explored for the encapsulation and release of a therapeutic agent, glucagon, that corrects low blood glucose levels. Accordingly, the release of glucagon from the nanocoil hydrogels is inversely related to glucose level. When evaluated in a mouse model of severe acute hypoglycemia, glucagon delivered from glucose-stabilized nanocoil hydrogels demonstrates increased protection compared to delivery of the agent alone or within a control nanocoil hydrogel that is not stabilized by glucose. 相似文献
