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Electrospinning is an important technique to fabricate nanofibers. In recent years, near-field electrospinning (NFES) has been developed to enhance the control of nanofiber deposition compared to conventional electrospinning, achieved by reducing the operating distance and electric field. This enables the construction of high-aspect ratio 3D structures in a self-aligned, layer-by-layer manner. However, the alignment of fiber deposition can be hindered by charge accumulation in the polymer fibers. Furthermore, a theoretical understanding of the underlying fiber deposition mechanism is still lacking. Herein, we present a numerical model for studying the charge transport, dissipation, and accumulation of NFES polymer fiber deposition. The model reveals that the presence of a trapped state in polymeric materials imposes limitations on the quality of charged fiber deposition. Moreover, the effect of different substrate materials on charge dissipation in fiber deposition is studied. To validate the model, we compare the simulation results with NFES experiments, demonstrating qualitative agreement. We also analyze the effect of the fiber materials and experimental parameters on the printing quality. This model provides an approach to analyze and optimize the operating parameters of NFES to achieve precise and stable nanofiber deposition. [ABSTRACT FROM AUTHOR]

The versatile properties of bipolar organic electrode materials have attracted considerable attention in the field of electrochemical energy storage (EES). However, their practical application is hindered by their inherent limitations including low intrinsic electrical conductivity, low specific capacity, and high solubility. Herein, a bipolar organic molecule combining both porphyrin and ferrocene moieties (CuDEFcP) [5,15‐bis(ethynyl)‐10,20‐di ferrocenyl porphinato]copper(II)) has been developed. It is proposed as a new organic electrode material with multifunctional application for rechargeable organic lithium‐based batteries (ROLBs) and dual‐ion organic symmetric batteries (SDIBs). Superior performance was delivered as cathode material in lithium based dual‐ion batteries (LDIBs), with a high initial discharge capacity of 300 mAh. g−1 at 0.2 A. g−1 and a reversible capacity of 58 mAh. g−1 after 5000 cycles at 1 A. g−1. However, employing it as an anode material in lithium‐ion batteries (LIBs), a reversible capacity of 295 mAh. g−1 at 0.2 A. g−1 was delivered. In SDIBs, in which CuDEFcP is used as both anode and cathode, an average discharge voltage of 2.4 V and an energy density of 261 Wh.kg−1 were achieved. [ABSTRACT FROM AUTHOR]

Exploring innovative strategies for molecular structuring of dynamic materials that combine self‐correcting intrinsic reversibility with the robustness of covalent bonds, has been a long‐standing objective from applications perspective in fields ranging from molecular engineering to nanotechnology and interfacial science. To establish dynamic covalent chemistry approaches combined with interfacial polymerization, herein, a distinct synthetic approach is reported to develop disulfide‐bridged 2D polymeric C3N3S3 triazine thin‐films by interfacial thiol‐disulfide dynamic exchange process crosslinking tritopic planar 1,3,5‐triazine‐2,4,6‐trithiol molecular tectons via intermolecular disulfide formation in the presence of I2 vapors at the air/water interface under redox condition. The resulting centimeter‐scale polymeric thin‐films are covalently cross‐linked, dynamic in nature, featuring tunable thickness (6–200 nm) and significant morphological variations are realized under the influence of varying reaction time, concentration and types of reducing agents. Notably, C3N3S3 polymer thin films exhibit a transflectance of around 99.5% in the range from 430 to 1800 nm, show high refractive indices (1.730–1.488) and optical anisotropy with uniaxial negative birefringence. The C3N3S3 free‐standing polymer thin‐films can be easily transferred to different substrates or possibly into application‐relevant forms for device fabrications, making this useful from materials application perspective. [ABSTRACT FROM AUTHOR]

Layer‐by‐layer synthesis of surface‐coordinated metal–organic frameworks (SURMOF) enables the assembly of asymmetric, dipolar linkers into non‐centrosymmetric pillar‐layered structures. Using appropriate substrate terminations can yield oriented growth with the dipoles aligned perpendicular to the surface. The aligned pillar linkers give rise to a built‐in electrostatic field. In addition, the non‐centrosymmetric structure of the SURMOF gives rise to intriguing nonlinear optical features, such as second harmonic generation. Previous research with methyl‐functionalized bipyridine pillar linkers have demonstrated that this approach works in principle, but so far the total degree of alignment is only very small. Herein, a multiscale modelling approach is presented for in‐silico SURMOF assembly to identify and overcome limitations in the growth of pillar‐layered SURMOFs and to develop a strategy to maximize linker alignment. Using master equation models and kinetic Monte Carlo simulations, it is found that the formation of a highly ordered state corresponding to the thermodynamic equilibrium is often prevented by long‐lasting transient effects. Based on ab initio binding energies for a wide selection of hypothetical pillar linkers, a fast‐binding, slow‐relaxation scheme is able to be identified during the SURMOF growth for a range of different pillar linkers. These observations allow them to derive a rational strategy for the design of novel linkers to yield SURMOF‐based non‐centrosymmetric materials with substantially improved properties. [ABSTRACT FROM AUTHOR]

Additive micro/nano‐manufacturing of polymeric precursors combining with a subsequent pyrolysis step enables the design‐controlled fabrication of micro/nano‐architected 3D pyrolytic carbon structures with complex architectural details. Pyrolysis results in a significant geometrical shrinkage of the pyrolytic carbon structure, leading to a structural dimension significantly smaller than the resolution limit of the involved additive manufacturing technology. Combining with the material properties of carbon and 3D architectures, architected 3D pyrolytic carbon exhibits exceptional properties, which are significantly superior to that of bulk carbon materials. This article presents a comprehensive review of the manufacturing processes of micro/nano‐architected pyrolytic carbon materials, their properties, and corresponding demonstrated applications. Acknowledging the "young" age of the field of micro/nano‐architected carbon, this article also addresses the current challenges and paints the future research directions of this field. [ABSTRACT FROM AUTHOR]

Li-ion batteries store electrical energy by electrochemically reducing Li ions from a liquid electrolyte in a graphitic electrode. During these reactions, electrolytic species in contact with the electrode particles form a solid-electrolyte interphase (SEI), a layer between the electrode and electrolyte. This interphase allows the exchange of Li ions between the electrode and electrolyte while blocking electron transfer, affecting the performance and life of the battery. A network of reactions in a small region determines the final structure of this interphase. This complex problem has been studied using different multi-scale computational approaches. However, it is challenging to obtain a comprehensive characterization of these models in connection with the effects of model parameters on the output, due to the computational costs. In this work, we propose an active learning workflow coupled with a kinetic Monte Carlo (kMC) model for formation of a SEI as a function of reaction barriers including electrochemical, diffusion, and aggregation reactions. This workflow begins by receiving an initial database from a design-of-experiment approach to train an initial Gaussian process classification model. By iterative training of this model in the proposed workflow, we gradually extended the model's validity over a larger subset of reaction barriers. In this workflow, we took advantage of statistical tools to reduce the uncertainty of the model. The trained model is used to study the features of the reaction barriers in the formation of a SEI, which allows us to obtain a new and unique perspective on the reactions that control the formation of a SEI. [ABSTRACT FROM AUTHOR]

Polymer pyrolysis has emerged as a versatile method to synthesize graphenoid (graphene like) materials with varying thickness and properties. The morphology of the thin film, especially the thickness, greatly affects the graphitizability and the properties of the graphenoid material. Using in situ current annealing inside a transmission electron microscope (TEM), the thickness‐dependent structural evolution of the polymer film with a special focus on thickness effects is followed. At high temperatures, thin samples form large graphene layers oriented parallel to the substrate, whereas in thick samples multi‐walled cage‐like structures are formed. Moleclar Dynamics (MD) simulations reveal a film thickness of 40 Å below which, the carbonized layers align parallel to the surface. For thicker samples, the orientation of the layers becomes increasingly misoriented starting from the surface to the center. This structural change can be attributed to the formation of bonded multi‐layers from the initially unsaturated activated edges. The resulting cage‐like structures are stable even during simulated annealing at temperatures as high as 3500 K. An atomistic understanding of the formation of these structures is presented. The results clearly indicate the critical effect of thickness on the graphitizability of polymers and provide a new understanding of the structural evolution during pyrolysis. [ABSTRACT FROM AUTHOR]

Solid electrolyte interphases (SEIs) form as reduction products at the electrodes and strongly affect battery performance and safety. Because SEI formation poses a highly nonlinear, complex multi‐physics problem over various lengths and time scales, traditional modeling approaches struggle to characterize SEI evolution solely with existing physical properties. To improve the characterization of SEIs, it proposes a data‐driven strategy for a virtual material design that learns to represent and characterize SEI formation with physical and data‐driven properties from kinetic Monte Carlo simulations. A Variational AutoEncoder with a property regressor learns data‐driven properties, which represent SEI configurations and correlate with physical target properties. This new neural network design encodes the high‐dimensional structural and reaction spaces into a lower‐dimensional latent space, while the property regressor orders the latent space by physical target properties. The model achieves high correlation scores between target and predicted properties from latent representations, thereby proving that the data‐driven properties enrich the expressiveness of SEI characterizations. [ABSTRACT FROM AUTHOR]

Manufacturing programmable materials, whose mechanical properties can be adapted on demand, is highly desired for their application in areas ranging from robotics, to biomedicine, or microfluidics. Herein, the inclusion of dynamic and living bonds, such as alkoxyamines, in a printable formulation suitable for two‐photon 3D laser printing is exploited. On one hand, taking advantage of the dynamic covalent character of alkoxyamines, the nitroxide exchange reaction is investigated. As a consequence, a reduction of the Young´s Modulus by 50%, is measured by nanoindentation. On the other hand, due to its "living" characteristic, the chain extension becomes possible via nitroxide mediated polymerization. In particular, living nitroxide mediated polymerization of styrene results not only in a dramatic increase of the volume (≈8 times) of the 3D printed microstructure but also an increase of the Young's Modulus by two orders of magnitude (from 14 MPa to 2.7 GPa), while maintaining the shape including fine structural details. Thus, the approach introduces a new dimension by enabling to create microstructures with dynamically tunable size and mechanical properties. [ABSTRACT FROM AUTHOR]

Due to its outstanding properties, graphene has emerged as one of the most promising 2D materials in a large variety of research fields. Among the available fabrication protocols, chemical vapor deposition (CVD) enables the production of high quality single-layered large area graphene. To better understand the kinetics of CVD graphene growth, multiscale modeling approaches are sought after. Although a variety of models have been developed to study the growth mechanism, prior studies are either limited to very small systems, are forced to simplify the model to eliminate the fast process, or they simplify reactions. While it is possible to rationalize these approximations, it is important to note that they have non-trivial consequences on the overall growth of graphene. Therefore, a comprehensive understanding of the kinetics of graphene growth in CVD remains a challenge. Here, we introduce a kinetic Monte Carlo protocol that permits, for the first time, the representation of relevant reactions on the atomic scale, without additional approximations, while still reaching very long time and length scales of the simulation of graphene growth. The quantum-mechanics-based multiscale model, which links kinetic Monte Carlo growth processes with the rates of occurring chemical reactions, calculated from first principles makes it possible to investigate the contributions of the most important species in graphene growth. It permits the proper investigation of the role of carbon and its dimer in the growth process, thus indicating the carbon dimer to be the dominant species. The consideration of hydrogenation and dehydrogenation reactions enables us to correlate the quality of the material grown within the CVD control parameters and to demonstrate an important role of these reactions in the quality of the grown graphene in terms of its surface roughness, hydrogenation sites, and vacancy defects. The model developed is capable of providing additional insights to control the graphene growth mechanism on Cu(111), which may guide further experimental and theoretical developments. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries (LIBs) are a widely used battery technology. During the initial LIB cycle, a passivation layer, called the solid electrolyte interphase (SEI), forms on the anode surface, which plays a crucial role in the performance and long‐term cyclability of LIBs. The overall mesoscale mechanisms of SEI formation and its composition remain elusive both in experimental and computational approaches. Here a multiscale approach to comprehensively characterize the growth and composition of the SEI based on a chemistry‐specific reaction network is presented. Generating an ensemble of over 50 000 simulations representing different reaction conditions, it is found that the organic SEI forms and grows in a solution‐mediated pathway by aggregation of SEI precursors far away from the surface via a nucleation process. The subsequent rapid growth of these nuclei leads to the formation of a porous layer that eventually covers the surface. This finding offers a solution to the paradoxical situation that SEI constituents can form only near the surface, where electrons are available, but does not stop growing when this narrow region is covered. The study is able to identify the key reaction parameters that determine SEI thickness, which pave the way to optimize battery performance and lifetime. [ABSTRACT FROM AUTHOR]

While materials based on organic molecules usually have either superior optoelectronic or superior chiral properties, the combination of both is scarce. Here, a crystalline chiroptical film based on porphyrin with homochiral side groups is presented. While the dissolved molecule has a planar, thus, achiral porphyrin core, upon assembly in a metal–organic framework (MOF) film, the porphyrin core is twisted and chiral. The close packing and the crystalline order of the porphyrin cores in the MOF film also results in excellent optoelectronic properties. By exciting the Soret band of porphyrin, efficient photoconduction with a high On‐Off‐ratio is realized. More important, handedness‐dependent circularly‐polarized‐light photoconduction with a dissymmetry factor g of 4.3×10−4 is obtained. We foresee the combination of such assembly‐induced chirality with the rich porphyrin chemistry will enable a plethora of organic materials with exceptional chiral and optoelectronic properties. [ABSTRACT FROM AUTHOR]

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Multivalent batteries show promising prospects for next‐generation sustainable energy storage applications. Herein, we report a polytriphenylamine (PTPAn) composite cathode capable of highly reversible storage of tetrakis(hexafluoroisopropyloxy) borate [B(hfip)4] anions in both Magnesium (Mg) and calcium (Ca) battery systems. Spectroscopic and computational studies reveal the redox reaction mechanism of the PTPAn cathode material. The Mg and Ca cells exhibit a cell voltage >3 V, a high‐power density of ∼∼3000 W kg−1 and a high‐energy density of ∼∼300 Wh kg−1, respectively. Moreover, the combination of the PTPAn cathode with a calcium‐tin (Ca−Sn) alloy anode could enable a long battery‐life of 3000 cycles with a capacity retention of 60 %. The anion storage chemistry associated with dual‐ion electrochemical concept demonstrates a new feasible pathway towards high‐performance divalent ion batteries. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)