Synthesis of 3D flower‐like zinc‐nitrilotriacetic acid (ZnNTA) mesocrystals and their conformal transformation to hierarchically porous N‐doped carbon superstructures is reported. During the ...solvothermal reaction, 2D nanosheet primary building blocks undergo oriented attachment and mesoscale assembly forming stacked layers. The secondary nucleation and growth preferentially occurs at the edges and defects of the layers, leading to formation of 3D flower‐like mesocrystals comprised of interconnected 2D micropetals. By simply varying the pyrolysis temperature (550–1000 °C) and the removal method of in the situ‐generated Zn species, nonporous parent mesocrystals are transformed to hierarchically porous carbon flowers with controllable surface area (970–1605 m2 g−1), nitrogen content (3.4–14.1 at%), pore volume (0.95–2.19 cm3 g−1), as well as pore diameter and structures. The carbon flowers prepared at 550 °C show high CO2/N2 selectivity due to the high nitrogen content and the large fraction of (ultra)micropores, which can greatly increase the CO2 affinity. The results show that the physicochemical properties of carbons are highly dependent on the thermal transformation and associated pore formation process, rather than directly inherited from parent precursors. The present strategy demonstrates metal‐organic mesocrystals as a facile and versatile means toward 3D hierarchical carbon superstructures that are attractive for a number of potential applications.
Metal‐organic mesocrystals with 3D flower‐like superstructures are solvothermally synthesized and employed as versatile precursors for hierarchically porous nitrogen‐doped carbon with flower‐like appearance that is difficult to access through conventional synthesis methods. The control over pyrolysis temperature and associated in situ generation of porogens leads to high nitrogen content and (ultra)micropores, which increase the CO2/N2 selectivity significantly.
All aqueous multiphase systems have attracted significant attention recently, in particular water-in-water Pickering emulsions. In here, polydopamine nanoparticles (PDP) are investigated as ...stabilizers for dextran and poly(ethylene glycol) (PEG)-based aqueous emulsions. Remarkably, stable emulsions are obtained from the all-biocompatible materials that can be broken either via dilution or surfactant addition. Further cross-linking of PDP via poly(acrylic acid) and carbodiimide strengthens the stability of emulsion droplets in a colloidosome-like structure. After cross-linking, demulsification via dilution or surfactant addition was largely hindered. The PDP-mediated formation of all aqueous emulsions is expected to be generalized to different types of water-in-water emulsions with other polymers and offers new opportunities in surface modification as well as microencapsulation.
Covalent modification of phenyl-modified carbon nitride with vinylthiazole groups via visible light induced grafting is reported. Modified structures express negative charge migration to the thiazole ...edges while the carbon nitride sheet remains positively charged in organic solutions. Such a phenomenon provides electrostatic stabilization of modified carbon nitride particles in organic media leading to highly organodispersible and colloidally stable carbon nitrides. The resulting structures can be homogeneously dispersed in organic solvents and can be cast to transparent films. The usefulness of such a processable colloidal carbon nitride building block is exemplified here by its high luminescence and inkjet printing of films.
Self‐assembly of double hydrophilic block copolymers (DHBCs) in water is an emerging area of research. The self‐assembly process can be derived from aqueous two‐phase systems that are composed of ...hydrophilic homopolymers at elevated concentration. Consecutively, DHBCs form self‐assembled structures like micelles, vesicles, or particles at high concentrations in water and without the use of external triggers that would change solubility of individual blocks. Careful choice of the two hydrophilic blocks and design of the polymer structure allows formation of self‐assembled structures with high efficiency. The present contribution highlights recent research in the area of DHBC self‐assembly, including the polymer types employed and strategies for crosslinking of the self‐assembled structures. Moreover, an overview of aqueous multiphase systems and theoretical considerations of DHBC self‐assembly are presented, as well as an outlook regarding potential future applications in areas such as the biomedical field.
Double hydrophilic block copolymers form self‐assembled structures in aqueous solution; for example, particles, micelles, or vesicles. The self‐assembly relies significantly on polymer concentration and utilized polymer blocks. Moreover, self‐assembled structures can be stabilized via crosslinking chemistry. Here, a variety of examples is reviewed with respect to formed structures and concentration range as well as theoretical background and aqueous multiphase systems.
Covalent bridges play a crucial role in the folding process of sequence-defined biopolymers. This feature, however, has not been recreated in synthetic polymers because, apart from some simple ...regular arrangements (such as block co-polymers), these macromolecules generally do not exhibit a controlled primary structure--that is, it is difficult to predetermine precisely the sequence of their monomers. Herein, we introduce a versatile strategy for preparing foldable linear polymer chains. Well-defined polymers were synthesized by the atom transfer radical polymerization of styrene. The controlled addition of discrete amounts of protected maleimide at precise times during the synthesis enabled the formation of polystyrene chains that contained positionable reactive alkyne functions. Intramolecular reactions between these functions subsequently led to the formation of different types of covalently folded polymer chains. For example, tadpole (P-shaped), pseudocyclic (Q-shaped), bicyclic (8-shaped) and knotted (α-shaped) macromolecular origamis were prepared in a relatively straightforward manner.
Effective, solution-processable designs of interfacial electron-transporting layers (ETLs) or hole-blocking layers are promising tools in modern electronic devices, e.g., to improve the performance, ...cost, and stability of perovskite-based solar cells. Herein, we introduce a facile synthetic route of thiazole-modified carbon nitride with 1.5 nm thick nanosheets which can be processed to a homogeneous, metal-free ETL for inverted perovskite solar cells. We show that thiazole-modified carbon nitride enables electronic interface enhancement via suppression of charge recombination, achieving 1.09 V in V oc and a rise to 20.17 mA/cm2 in J sc. Hence, this report presents the successful implementation of a carbon-nitride-based structure to boost charge extraction from the perovskite absorber toward the electron transport layer in p-i-n devices.
Aqueous multiphase systems have attracted a lot of interest recently espeically due to target applications in the biomedical field, cosmetics, and food. In turn, water‐in‐water Pickering emulsions ...are investigated frequently. In here, graphitic carbon nitride (g‐CN) stabilized water‐in‐water Pickering emulsions are fabricated via the dextran and poly(ethylene glycol)‐based aqueous two‐phase system. Five different derivatives of g‐CN as the Pickering stabilizer are described and the effect of g‐CN concentration on droplet sizes is investigated. Stable emulsions (up to 16 weeks) are obtained that can be broken on purpose via various approaches, including dilution, surfactant addition, and most notably light irradiation. The novel approach of water‐in‐water emulsion stabilization via g‐CN opens up considerable advances in aqueous multiphase systems and may also introduce photocatalytic properties.
A graphitic carbon nitride‐stabilized water‐in‐water emulsion from the poly(ethylene glycol)‐dextran aqueous two‐phase system is described that can be demulsified on purpose via dilution, surfactant addition, and light irradiation.
Here we report a facile synthesis of carbon nitride-based hydrogels with adjustable shapes, ranging from cylinder to tube and thin sheet, by photopolymerization process in confined templates. The ...fabricated hydrogel shows enhanced mechanical properties compared to the reference gel without carbon nitride incorporation, good adsorption capacity, and promising photocatalytic activity toward hydrogen production. Meanwhile, the hydrogel also exhibits selective pollutants adsorption properties that could be attributed to the negative-charged carbon nitride as well as relatively high stability alongside enhanced light harvesting. The novel carbon nitride-based hydrogels offer a facile approach as photocatalyst and open up many opportunities for smart-catalyst design with adjustable reaction sites.
In the present Feature Article, a kinetic strategy for controlling the microstructure of synthetic polymer chains prepared via a radical chain‐growth polymerization process is presented. This ...approach was recently developed in our laboratory and relies on the controlled kinetic addition of ultrareactive N‐substituted maleimides during the atom transfer radical polymerization of styrene. This method is experimentally straightforward and can be applied to a broad library of functional N‐substituted maleimides. Thus, this platform allows synthesis of unprecedented polymer materials such as 1D macromolecular arrays. The basic kinetic requirements, the experimental conditions, and the synthetic scope of this approach are discussed in details herein.
The controlled radical copolymerization of styrene with N‐substituted maleimides allows preparation of unique polymer microstructures. Indeed, we reported in recent years that small amounts of N‐substituted maleimides can be placed at specific locations in linear polystyrene chains. Herein, we describe in details this research advance. The kinetic concept, the experimental conditions and the scope of this novel strategy are discussed in this feature article.
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