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Covalent organic frameworks (COFs) are crystalline, nanoporous materials of interest for various applications. However, current COF synthetic routes lead to insoluble aggregates which hamper processing and prohibit their use in many applications. Here, we report a novel COF synthesis method that produces a stable, homogeneous suspension of crystalline COF nanoparticles. Our approach involves the use of a polar solvent, di-acid catalyst, and slow reagent mixing procedure at elevated temperatures which all together enable access to crystalline COF nanoparticle suspension that does not aggregate or precipitate when kept at elevated temperatures. On cooling, the suspension undergoes a thermoreversible gelation transition to produce crystalline and highly porous COF materials. We demonstrate that this method enables the preparation of COF monoliths, membranes, and films using conventional solution processing techniques. We show that the modified synthesis approach is compatible with various COF chemistries, including both large- and small-pore imine COFs, hydrazone-linked COFs, and COFs with rhombic and hexagonal topology, and in each case, we demonstrate that the final product has excellent crystallinity and porosity. The final materials contain both micro- and macropores, and the total porosity can be tuned through variation of sample annealing. Dynamic light scattering measurements reveal the presence of COF nanoparticles that grow with time at room temperature, transitioning from a homogeneous suspension to a gel. Finally, we prepare imine COF membranes and measure their rejection of polyethylene glycol (PEG) polymers and oligomers, and these measurements exhibit size-dependent rejection of PEG solutes. This work demonstrates a versatile processing strategy to create crystalline and porous COF materials using solution processing techniques and will greatly advance the development of COFs for various applications.

Background Mass vaccination has been a key strategy in effectively containing global COVID-19 pandemic that posed unprecedented social and economic challenges to many countries. However, vaccination rates vary across space and socio-economic factors, and are likely to depend on the accessibility to vaccination services, which is under-researched in literature. This study aims to empirically identify the spatially heterogeneous relationship between COVID-19 vaccination rates and socio-economic factors in England. Methods We investigated the percentage of over-18 fully vaccinated people at the small-area level across England up to 18 November 2021. We used multiscale geographically weighted regression (MGWR) to model the spatially heterogeneous relationship between vaccination rates and socio-economic determinants, including ethnic, age, economic, and accessibility factors. Results This study indicates that the selected MGWR model can explain 83.2% of the total variance of vaccination rates. The variables exhibiting a positive association with vaccination rates in most areas include proportion of population over 40, car ownership, average household income, and spatial accessibility to vaccination. In contrast, population under 40, less deprived population, and black or mixed ethnicity are negatively associated with the vaccination rates. Conclusions Our findings indicate the importance of improving the spatial accessibility to vaccinations in developing regions and among specific population groups in order to promote COVID-19 vaccination.

The connectivity of building units for 3D covalent organic frameworks (COFs) has long been primarily 4 and 6, which have severely curtailed the structural diversity of 3D COFs. Here we demonstrate the successful design and synthesis of a porphyrin based, 8-connected building block with cubic configuration, which could be further reticulated into an unprecedented interpenetrated pcb topology by imine condensation with linear amine monomers. This study presents the first case of high-connectivity building units bearing 8-connected cubic nodes, thus greatly enriching the topological possibilities of 3D COFs.

Liquid crystal elastomers are stimuli-responsive, shape-shifting materials. They typically require high temperatures for actuation which prohibits their use in many applications, such as biomedical devices. In this work, we demonstrate a simple and general approach to tune the order-to-disorder transition temperature (

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Background The global Covid-19 pandemic has caused numerous deaths and illnesses, posing unprecedented social and economic challenges to many countries. One of the key strategies to contain the pandemic is mass vaccination programme. However, vaccination rates vary across space and socio-economic factors, and are likely to depend on the accessibility to vaccination services. There is a lack of quantitative understanding of how spatial-socio-economic factors influence the Covid-19 vaccination rates in England. Methods We investigated the percentage of over-18 fully vaccinated people at the small-area level across England up to 18 November 2021. We used (multiscale) geographically weighted regression to model the spatially heterogeneous relationship between vaccination rates and socio-economic determinants, including ethnic, age, economic, and accessibility factors. Results This study indicates that the selected model can explain 83.2% of the total variance of vaccination rates. The variables exhibiting a positive association with vaccination rates in most areas include proportion of population over 40, car ownership, average household income, and accessibility to vaccination. In contrast, population under 40, low multiple deprivation level, and black or mixed ethnicity are negatively associated with the vaccination rates. Conclusions Our findings indicate the importance of improving the spatial accessibility to vaccinations in developing regions and among specific population groups in order to promote Covid-19 vaccination.

Molecular imprinting is a promising strategy to selectively adsorb viruses, but it requires discerning and validating epitopes that serve as effective imprinting templates. In this work, glycoprotein-imprinted particles were synthesized for coronavirus capture. Adsorption was maximized at pH 6 (the glycoprotein isoelectric point) where the glycoprotein-imprinted particles outperformed non-imprinted particles, adsorbing 4.96 × 10

Covalent organic frameworks (COFs) are crystalline organic materials of interest for a wide range of applications due to their porosity, tunable architecture, and precise chemistry. However, COFs are typically produced in powder form and are difficult to process. Herein, we report a simple and versatile approach to fabricate macroscopic, crystalline COF gels and foams. Our method involved the use of dimethyl sulfoxide as a solvent and acetic acid as a catalyst to first produce a COF gel. The COF gel was then washed, dried, and reactivated to produce a macroscopic, crystalline, porous COF foam. We demonstrated this synthesis for six different imine COFs and found that the crystallinities and porosities of the COF foams matched those of COF powders. Electron microscopy revealed a robust hierarchical pore structure, and we showed that the COF foams can be used as absorbents in oil-water separations, for the removal of organic and inorganic micropollutants, and for the capture and retention of iodine. This study provides a versatile and simple approach for the fabrication of COF foams and will provide novel routes for incorporating COFs in applications that require macroscopic, porous materials.

Many scholars have sought effective ways to encourage people to cycle more. A considerable amount of effort has focused on the role of dedicated cycling infrastructure. However, knowledge on the roles and interactions of other factors that are influential in addition to infrastructure in cities where the cycling network is well-developed remains incomplete. In this study, we examined how various individual-level attributes, namely psychological, habitual, and socio-demographic, in addition to the built environment characteristics relate to cycling behaviour of employees of the Erasmus University Rotterdam, in the Netherlands, where comprehensive cycling infrastructure is provided. Specifically, we investigated how these factors relate to being a cyclist or not, as well as how they are associated with regular and irregular cyclists. An online survey was conducted among employees of the university and logistic regression models were utilized for the analyses. Our results showed that the perception of behavioural control is consistently correlated with different cycling behaviour while controlling for socio-demographic and residential built environment factors. Also, we found evidence supporting a trade-off between attitudes and habit across different types of commuters. Socio-demographic factors such as gender and year of immigration to the Netherlands are only related to being engaged in cycling but not to increasing the level of engagement among employees who cycled already. The type of residential area and population/business density at destinations does not appear as a consistent covariate. We concluded that psychological and habitual factors play key roles in encouraging cycling in a city with an extensive cycling infrastructure network.

Understanding how access to public transport varies across space is important in a wide variety of urban research. For instance, how is access related to risks of unemployment? How does access to urban amenities capitalise into land prices? Does good accessibility drive gentrification? Much research has focused on distance-based measures because they are straightforward to derive. However, they often assume access to a car since mobility is seen as being equally possible in all directions. This is not a justifiable assumption in many cases, particularly for lower income groups in urban areas. It would therefore be useful to have accessibility measures which assume travel by public transport. The present work addresses this unmet need. It offers a series of accessibility indicators at the level of the Lower Super Output Area/Datazone (LSOA/DZ) covering the whole of Great Britain (GB) in the United Kingdom (UK). Indicators by public transport include a range of key amenities and services such as: employment; general practice (GP) surgery; hospital; grocery store; supermarket; primary school; secondary school; and urban centre. Code to create the derived indicators is openly available for other researchers to use and customise in the following GitHub repository:https://github.com/rafavdz/access_uk.

The sensitivity of covalent organic frameworks (COFs) to pore collapse during activation processes is generally termed activation stability, and activation stability is important for achieving and maintaining COF crystallinity and porosity which are relevant to a variety of applications. However, current understanding of COF stability during activation is insufficient, and prior studies have focused primarily on thermal stability or on the activation stability of other porous materials, such as metal-organic frameworks (MOFs). In this work, we demonstrate and implement a versatile experimental approach to quantify activation stability of COFs and use this to establish a number of relationships between their pore size, the type of pore substituents, pore architecture, and structural robustness. Additionally, density functional theory calculations reveal the impact on both inter-and intra-layer interactions, which govern activation stability, and we demonstrate that activation stability can be systematically tuned using a multivariate synthesis approach involving mixtures of functionalized and unfunctionalized COF building blocks. Our findings provide novel fundamental insights into the activation stability of COFs and offer guidance for the design of more robust COFs.

Bottlebrush polymers can be used to introduce novel surface properties including hydrophilicity, stimuli-responsiveness, and reduced friction forces. However, simple, general, and efficient approaches to cross-linking bottlebrush polymer films and coatings are limited. Here, we report that bottlebrush polymers with an unsaturated polynorbornene backbone and thiol-terminated side chains can be cross-linked on demand by UV irradiation to produce uniform and insoluble bottlebrush polymer coatings. To quantify the kinetics and efficiency of cross-linking by UV exposure (254 nm), we measured the normalized residual thickness (NRT) of bottlebrush and linear polymer films after UV exposure and solvent washing. For bottlebrush polymers with thiol-terminated polystyrene (PS) side chains, the NRT exceeded 60% for a UV dose of 1.0 J/cm2, while unfunctionalized linear PS required a dose of 7.9 J/cm2 to achieve similar NRT values. Rapid UV-induced cross-linking of the bottlebrush PS was attributed to the thiol–ene coupling of the thiol-terminated side chains with the unsaturated polynorbornene backbones, as demonstrated through FTIR measurements and control studies involving bottlebrush polymers with saturated backbones. To establish the broader applicability of this approach, UV-induced cross-linking was demonstrated for thin films of bottlebrush polymers with thiol-terminated poly­(methyl acrylate) (BB-PMMA-SH) side chains and those with poly­(ethylene glycol) (BB-PEG) and poly­(lactic acid) (BB-PLA) side chains which do not contain thiol end groups. UV-induced cross-linking of BB-PEG and BB-PLA films required the use of a multifunctional thiol additive. Finally, we demonstrated that bottlebrush polymer multilayers can be fabricated through sequential deposition and UV-induced cross-linking of different bottlebrush polymer chemistries. The cross-linking process outlined in this work is simple, general, and efficient and produces solvent-resistant coatings that preserve the unique properties and functions of bottlebrush polymers.

Bioelectronics brings together the fields of biology and microelectronics to create multifunctional devices with the potential to address longstanding technological challenges and change our way of life. Microbial electrochemical devices are a growing subset of bioelectronic devices that incorporate naturally occurring or synthetically engineered microbes into electronic devices and have broad applications including energy harvesting, chemical production, water remediation, and environmental and health monitoring. The goal of this Viewpoint is to highlight recent advances and ongoing challenges in the rapidly developing field of microbial bioelectronic devices, with an emphasis on materials challenges. We provide an overview of microbial bioelectronic devices, discuss the biotic-abiotic interface in these devices, and then present recent advances and ongoing challenges in materials related to electron transfer across the abiotic-biotic interface, microbial adhesion, redox signaling, electronic amplification, and device miniaturization. We conclude with a summary and perspective of the field of microbial bioelectronics.

The bicontinuous microemulsion (BμE) phase is an equilibrium morphology characterized by cocontinuous domains, high interfacial areas, and nanoscale domain dimensions. These characteristics make the BμE potentially suitable for use in organic photovoltaic applications. Here, we use a combination of simulations and experiments to investigate the equilibrium morphologies formed by a ternary blend of conjugated polymer, all-conjugated diblock copolymer, and fullerene derivative PCBM. Using coarse-grained simulations, we identify the blend compositions that are most likely to result in donor/acceptor morphologies resembling the BμE. Experimentally, we probe these compositions through transmission electron microscopy and grazing-incidence X-ray scattering measurements. We demonstrate that all-conjugated block copolymer additives can be used to produce thermally stable, cocontinuous donor/acceptor morphologies at higher additive contents and longer annealing times than previously reported. These results demonstrate that conjugated BCP compatibilizers can be used as a means to achieve equilibrium, cocontinuous morphologies in donor/acceptor blends.

Covalent organic frameworks (COFs) are crystalline, porous organic materials that are promising for applications including catalysis, energy storage, electronics, gas storage, water treatment, and ...

Designing a structurally stable anode with a high reversible capacity for sodium ion batteries (SIBs) is particularly crucial so that batteries are able to meet the requirements for large-scale applications in grid electrical energy storage. Polyaromatic hydrocarbons (PAHs) are organic molecules with well-defined structures that demonstrate excellent performance in lithium storage. Based on our well-established correlation between battery property and molecular structure, for the first time, we applied a recently synthesized hexabenzocoronene (HBC) and corresponding derivate HBC–OMe to engage in sodium storage. The HBC molecule forms self-assemblies with a long-range ordered face-center cubed (fcc) structure due to the interaction between two HBC moieties. Such a unique 3D structure is expected to generate a strong π–π interaction between flakes and thus yield amazing durability during the long-term cycling process. In addition, the surface-dominated Na+ storage mechanism can facilitate the Na+ transport kinetics and simultaneously alleviate the structural strain during charging–discharging cycles. Benefiting from the coupling effect of the surface-driven capacitive process and the robust 3D self-assembled hierarchical nature, an oxygen-containing sample, HBC–OMe, exhibited an extraordinary sodium storage capability, attaining a high capacity of 506 mA h g−1 at 0.1 A g−1 with excellent rate capability (217 mA h g−1 at 5 A g−1) and superior long-term cycling performance (290 mA h g−1 at 2 A g−1 with negligible capacity fade after 1000 cycles).

Covalent organic frameworks (COFs) are crystalline porous materials linked by dynamic covalent bonds. Dynamic chemistries enable the transformation of an initially amorphous network into a porous a...

State-of-the-art polymeric membranes are unable to perform the high-precision ion separations needed for technologies essential to a circular economy and clean energy future. Coordinative interactions are a mechanism to increase sorption of a target species into a membrane, but the effects of these interactions on membrane permeability and selectivity are poorly understood. We use a multilayered polymer membrane to assess how ion-membrane binding energies affect membrane permeability of similarly sized cations: Cu 2+ , Ni 2+ , Zn 2+ , Co 2+ , and Mg 2+ . We report that metals with higher binding energy to iminodiacetate groups of the polymer more selectively permeate through the membrane in multisalt solutions than single-salt solutions. In contrast, weaker binding species are precluded from diffusing into the polymer membrane, which leads to passage proportional to binding energy and independent of membrane thickness. Our findings demonstrate that selectivity of polymeric membranes can markedly increase by tailoring ion-membrane binding energy and minimizing membrane thickness.

Hexavalent chromium Cr(VI) is a highly toxic groundwater contaminant. In this study, we demonstrate a selective electrochemical process tailored for removal of Cr(VI) using a hybrid MOF@rGO nanomaterial synthesized by

The exploration of poly(tert-butyl methacrylate)-block-poly(4-vinylpyridine), PtBMA-b-P4VP, as a precursor material for the creation of nanostructured films with oppositely charged domains is repor...

Increasing demand for portable electronic devices, electric vehicles, and grid scale energy storage has spurred interest in developing high-capacity rechargeable lithium-ion batteries (LIBs). Silic...

Recycling systems aboard spacecraft are currently limited to approximately 80% water recovery from urine. To address challenges associated with odors, contamination, and microgravity fluid flow phenomena, current systems use toxic pretreatment chemicals, filters, and rotary separators. Herein, a semipassive and potentially contaminant- and biofouling-free approach to spacecraft urine processing is developed by combining passive liquid–gas separation, nanophotonic pasteurization, and noncontact Leidenfrost droplet distillation. The system aims to achieve >98% water recovery from wastewater streams in zero, Lunar, Martian, and terrestrial gravitational environments. The surfaces of the phase separator are coated with carbon black nanoparticles that are irradiated by infrared light-emitting diodes (LEDs) producing hyperlocal heating and pasteurization during urine collection, separation, and storage. For the prescribed flow rate and timeline, the urine is then introduced into a heated 8.5-m-long helical hemicircular aluminum track. The low pitch and the high temperature of the track combine to establish weakly gravity-driven noncontact Leidenfrost droplet distillation conditions. In our technology demonstrations, salt-free distillate and concentrated brine are successfully recovered from saltwater feed stocks. We estimate equivalent system mass metrics for the approach, which compare favorably to the current water recovery system aboard the International Space Station.

Organic additives known as modulators have been used to improve the crystallinity of covalent organic frameworks (COFs) and metal–organic frameworks (MOFs). Here, we demonstrate that benzaldehyde is an effective modulator for enhancing the crystallinity and porosity of imine-linked covalent organic frameworks (COFs). We varied the amount of benzaldehyde added during COF synthesis and found increased crystallinity and surface areas through powder X-ray diffraction (PXRD) and nitrogen gas adsorption measurements, respectively. The improved crystallinity and increased surface area were attributed to the reduced kinetics for COF nucleation and growth, which produced more ordered and crystalline COF materials. This work provides a simple, efficient and general way to improve the crystallinity and porosity of imine-linked COFs and furthers understanding of the role of modulators in the synthesis of COFs.

Silicon anodes potentially offer a volumetric energy storage capacity significantly greater than that of commercial graphitic carbon anodes, but silicon electrodes exhibit poor stability under reversible charging and discharging. This has been attributed to several factors including large volume changes of silicon during battery operation, the non-passivating nature of the Si surface which can result in uncontrolled growth of solid-electrolyte interface layers, and reactivity between the binder and lithiated silicon. To address these challenges, researchers have developed innovative compositions and architectures of polymer binders aimed at increasing storage capacities and improving stability. Polymer binders serve multiple functions in battery electrodes including maintaining adhesion between the electrode and current collector and cohesion of the electrode as a whole, ensuring the stability of the solid electrolyte layer that forms on the surface of silicon, and in some cases providing electronic and ionic conductivity. The goal of this review is to identify and critically evaluate underlying molecular design principles applied to the development of polymeric binders for silicon anodes. Molecular design principles include molecular functionalities, architectures, or compositions that can produce a desired physical or chemical property. The review specifically focuses on the molecular features of binders that facilitate self-healing, electronic conductivity, mechanical performance, and electrochemical performance.

BackgroundEnvironmental chemical exposures are likely making important contributions to current levels of infertility and its increasing incidence. Yet the US produces high volumes of industrial chemicals for which there is limited data on their potential human reproduction toxicity. Current assays typically used in policy and regulatory settings involve costly and timeconsuming whole-animal rodent tests which limit the rapidity with which one can assess the thousands of chemicals yet to be tested.ObjectiveOur aim was to develop a fast and reliable strategy to evaluate a large number of chemicals for reproductive toxicity by developing a high-throughput toxicity assessment using the yeast S. cerevisiae.MethodsYeast are chronically exposed to each environmental chemical at two doses, 30 μM and 100 μM, in a 96-well plate-based format throughout gametogenesis. Non-gametes are removed and chemicals are washed away before gamete viability is measured using absorbance at 600 nm to produce growth curves. The difference in time at half-maximal saturation with and without exposure is used to determine the extent of reproductive toxicity.ResultsWe validated our assay using bisphenol A (BPA), a well-established mammalian reproductive toxicant. We find that BPA in yeast has similar detrimental effects in meiosis as shown in worms and mammals. Competition assays with BPA analogs reveal that two of out of 19 BPA analogs examined (bisphenol E and 17β-estradiol) show synergistic effects with BPA at doses tested and none show antagonistic effects. Out of 179 additional environmental chemicals, we designated 57 chemicals as reproductively toxic. Finally, by comparing chemicals in our cohort that have been evaluated for reproductive toxicity in mammalian studies, we find a statistically significant association between toxic chemicals in yeast and mammals.ConclusionWe show that a high-throughput assay using yeast may be a useful approach for rapidly and reliably identifying chemicals that pose a reproductive risk.

Fair and meaningful device per- formance comparison among luminescent solar concentrator- photovoltaic (LSC-PV) reports cannot be realized without a gen- eral consensus on reporting stan- dards in LSC-PV research. There- fore, it is imperative to adopt standardized characterization protocols for these emerging types of PV devices that are consistent with other PV devices. This commentary highlights several common limitations in LSC literature and summarizes the best practices moving for- ward to harmonize with standard PV reporting, considering the greater nuances present with LSC-PV. Based on these prac- tices, a checklist of actionable items is provided to help stan- dardize the characterization/re- porting protocols and offer a set of baseline expectations for au- thors, reviewers, and editors. The general consensus combined with the checklist will ultimately guide LSC-PV research towards reliable and meaningful ad- vances.

The composition of polymer blends near interfaces can differ from the average blend composition because the attraction of each polymer toward surfaces is controlled by its chemistry, size, and arch...

Bottlebrush polymers are complex macromolecules with tunable physical properties dependent on the chemistry and architecture of both the side chains and the backbone. Prior work has demonstrated that bottlebrush polymer additives can be used to control the interfacial properties of blends with linear polymers but has not specifically addressed the effects of bottlebrush side chain microstructures. Here, using a combination of experiments and self-consistent field theory (SCFT) simulations, we investigated the effects of side chain microstructures by comparing the segregation of bottlebrush additives having random copolymer side chains with bottlebrush additives having a mixture of two different homopolymer side chain chemistries. Specifically, we synthesized bottlebrush polymers with either poly(styrene-ran-methyl methacrylate) side chains or with a mixture of polystyrene (PS) and poly(methyl methacrylate) (PMMA) side chains. The bottlebrush additives were matched in terms of PS and PMMA compositions, and they were blended with linear PS or PMMA chains that ranged in length from shorter to longer than the bottlebrush side chains. Experiments revealed similar behaviors of the two types of bottlebrushes, with a slight preference for mixed side-chain bottlebrushes at the film surface. SCFT simulations were qualitatively consistent with experimental observations, predicting only slight differences in the segregation of bottlebrush additives driven by side chain microstructures. Specifically, these slight differences were driven by the chemistries of the bottlebrush polymer joints and side chain end-groups, which were entropically repelled and attracted to interfaces, respectively. Using SCFT, we also demonstrated that the interfacial behaviors were dominated by entropic effects with high molecular weight linear polymers, leading to enrichment of bottlebrush near interfaces. Surprisingly, the SCFT simulations showed that the chemistry of the joints connecting the bottlebrush backbones and side chains played a more significant role compared with the side chain end groups in affecting differences in surface excess of bottlebrushes with random and mixed side chains. This work provides new insights into the effects of side chain microstructure on segregation of bottlebrush polymer additives.

Charged and partially fluorinated hydrogels are demonstrated to be a promising new approach to selectively uptake PFAS contaminants in water.