Atomic layer deposition (ALD) is a versatile technique for engineering the surfaces of porous polymers, imbuing the flexible, high-surface-area substrates with inorganic and hybrid material properties. Previously reported enhancements include fouling resistance, electrical conductance, thermal stability, photocatalytic activity, hydrophilicity, and oleophilicity. However, there are many poorly understood phenomena that introduce challenges in applying ALD to porous polymers. In this paper, we address five common challenges and ways to overcome them: (1) entrapped precursor, (2) embrittlement, (3) film fracture, (4) deformation, and (5) pore collapse. These challenges are often interrelated and can exacerbate one another. To investigate these phenomena, we applied various ALD chemistries to porous polymers including polyethersulfone, polysulfone, polyvinylidene fluoride, and polycarbonate track-etched membranes. Reaction-diffusion modeling revealed why certain precursors and processing conditions result in embrittling subsurface material growth, entrapment of unreacted precursors, and nongrowth. We quantify the limits of ALD processing temperatures that are dictated by thermal expansion mismatch and can lead to fractured ALD films. The results herein allow us to make recommendations to avoid, mitigate, or overcome the difficulties encountered when performing ALD and plasma-enhanced ALD on porous polymers. We intend this article to serve as a “lessons learned” guide informed by previous experience to provide a better understanding of the difficulties and limitations of ALD on porous polymers and knowledge-based guidelines for successful depositions. This knowledge can accelerate future research and help experimentalists navigate and troubleshoot as they expose porous polymers to reactive precursor vapors.

Ion uptake plays a critical role in membrane separations used for water purification and electro-membrane processes. Although models of ion uptake usually consider free dissociated ions, ion-pairing was suggested to play an important role as well and but its understanding in the context of membrane transport is still insufficient. The paper systematically develops the pore model of ion-pairing in membranes, which considers the membrane as a micro-heterogeneous system, composed of interspersed water-rich domains (pores accommodating ions) and a low-dielectric matrix. It is shown that this picture significantly departs from the predictions of the primitive model of the membrane as a uniform dielectric, in which dielectric exclusion and pairing of ions are rigidly related thus pairing of mobile ions is always negligible. Within the pore model, the effect of the ion-pairing constant enhanced by the low-dielectric properties of the matrix may outweigh the opposite effect of dielectric exclusion thereby mobile ions may be present within the membrane mainly as ion-pairs rather than free ions. We discuss various implications of this result for salt and ion uptake, transport, and conductance in neutral and charged membranes and outline needs for further research towards predictive modeling.

Oil and water phases placed on top of a solid surface respond differently to a MHz-level surface acoustic wave (SAW) propagating in the solid due to their different surface tensions and the corresponding capillary stresses. We observe that, under SAW excitation, oil films are extracted continuously from sessile drops of silicone-oil/water/surfactant mixtures. The mechanism responsible for the extraction of oil from the mixtures is the acoustowetting phenomenon: the low surface tension oil phase leaves the mixture in the form of `fingers' that initially spread over the solid in the direction transverse to that of the SAW. Once away from the drop the oil spreads on the solid surface in the direction opposite that of the SAW, as in classic studies on acoustowetting. The high surface tension water phase remains at rest. Increasing the SAW intensity and oil content in the mixtures enhances the rate at which oil leaves the emulsion. We further observe that the oil film develops free surface instabilities in the form of periodic spatial variations, as well as the formation of spatial gradients in the emulsion concentrations in the presence of SAW. Our study suggests the potential for using SAW to remove oil from oil-in-water mixtures to facilitate the small-scale separation of water and oil phases. Furthermore, we describe the peculiar physical effects leading to acoustic-capillary flow instabilities and SAW-induced emulsion dynamics.

Organoids mimic human organ function, offering insights into development and disease. However, non-destructive, real-time monitoring is lacking, as traditional methods are often costly, destructive, and low-throughput. In this article, a non-destructive chemical tomographic strategy is presented for decoding cyto-proteo-genomics of organoid using volatile signaling molecules, hereby, Volatile Organic Compounds (VOCs), to indicate metabolic activity and development of organoids. Combining a hierarchical design of graphene-based sensor arrays with AI-driven analysis, this method maps VOC spatiotemporal distribution and generate detailed digital profiles of organoid morphology and proteo-genomic features. Lens- and label-free, it avoids phototoxicity, distortion, and environmental disruption. Results from testing organoids with the reported chemical tomography approach demonstrate effective differentiation between cyto-proteo-genomic profiles of normal and diseased states, particularly during dynamic transitions such as epithelial-mesenchymal transition (EMT). Additionally, the reported approach identifies key VOC-related biochemical pathways, metabolic markers, and pathways associated with cancerous transformations such as aromatic acid degradation and lipid metabolism. This real-time, non-destructive approach captures subtle genetic and structural variations with high sensitivity and specificity, providing a robust platform for multi-omics integration and advancing cancer biomarker discovery.

The pressure-dependent reactions on the N₂H₃ potential energy surface (PES) have been investigated using CCSD(T)-F12/aug-cc-pVTZ-F12//B2PLYP-D3/aug-cc-pVTZ. This study expands the N₂H₃ PES beyond the previous literature by incorporating a newly identified isomer, NH₃N, along with additional bimolecular reaction channels associated with this isomer, namely NNH + H₂ and H₂NN(S) + H. Rate coefficients for all relevant pressure-dependent reactions, including well-skipping pathways, are predicted using a combination of ab initio transition state theory and master equation simulations. The dominant product of the NH₂ + NH(T) recombination is N₂H₂ + H, while at high pressures and low temperatures, N₂H₃ formation becomes significant. Similarly, collisions involving H₂NN(S) + H predominantly produce N₂H₂ + H. Secondary reactions such as H₂NN(S) + H ⇌ NNH + H₂ and H₂NN(S) + H ⇌ NH₂ + NH(T) are found to play a significant role at high temperatures across all examined pressures, while H₂NN(S) + H ⇌ NH₃N becomes prominent only at high pressures. Notably, none of these four H₂NN(S) reactions have been included with pressure-dependent rate coefficients in previous NH₃ oxidation models. The rate coefficients reported here provide valuable insights for modeling the combustion of ammonia, hydrazine, and their derivatives in diverse environments.

Cardiovascular diseases, which cause ≈10 million deaths annually, underscored the importance of effective blood pressure (BP) monitoring. Traditional devices, however, faced limitations that hindered the adoption of continuous monitoring technologies. Flexible triboelectric nanogenerator (TENG) sensors, known for their rapid response, high sensitivity, and cost-effectiveness, presented a promising alternative. Enhancing their ability to capture weak biological signals can be achieved by optimizing the material's friction coefficient and expanding the effective contact area. In this work, a flexible microcolumn-based TENG sensor with high sensitivity is developed by fabricating microcolumns of carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites on porous polyethylene terephthalate (PET) membranes using template etching and integrating these with fluorinated ethylene propylene (FEP) film. With the enhancement of microcolumn structure, the sensor possessed high sensitivity and good response, enabling it to effectively and accurately detect subtle physiological changes such as radial pulses and fingertip pulsations, with pulse wave signals highly consistent with the interbeat intervals of electrocardiograms. Leveraging these capabilities, a non-invasive dynamic BP monitoring system capable of continuous beat-to-beat BP monitoring is developed. This advancement enables easier and more effective health monitoring, empowering individuals to better manage their health and improve personalized medical care.

The solution-diffusion (SD) model has faithfully served membrane research for decades, however, recently reported discrepancies between molecular dynamics and experiments reignited a debate on its validity. This study places on a solid foundation the picture of SD as mechanical-transport coupling put forward recently. The full set of coupled relations is rigorously derived using a variational approach. The approach is also generalized to the case of coupled solvent and solute transport and the result is equivalent to the classical irreversible thermodynamics relations, the Spiegler-Kedem model, augmented with a pressure-stress relation. This suggests a more general interpretation of SD, whereby what differentiates SD form the pore-flow is the nature of the driving force or "solution", when the single-phase membrane phase exchanges both mechanical and chemical energy with the permeating solvent, rather than "diffusion", i.e., specific mechanism behind solvent-membrane friction. The paper also elaborates on the cases of the supported and open films, representative of experiments and molecular simulations, which removes the reported apparent discrepancies. The presented study then closes a critical gap between simulations and real-world processes and applications, opening opportunities for new insights and design of next-generation materials.

A comprehensive approach enabling a quantitative interpretation of poly-l-arginine (PARG) adsorption kinetics at solid/electrolyte interfaces was developed. The first step involved all-atom molecular dynamics (MD) modeling of physicochemical characteristics yielding PARG molecule conformations, its contour length, and the cross-section area. It was also shown that PARG molecules, even in concentrated electrolyte solutions (100 mM NaCl), assume a largely elongated shape with an aspect ratio of 36. Using the parameters derived from MD, the PARG adsorption kinetics at the silica/electrolyte interface was calculated using the random sequential adsorption approach. These predictions were validated by optical reflectometry measurements. It was confirmed that the molecules irreversibly adsorbed in the side-on orientation and their coverage agreed with the elongated shape of the PARG molecule predicted from the MD modeling. These theoretical and experimental results were used for the interpretation of the quartz crystal microbalance measurements carried out under various pH conditions. A comprehensive analysis unveiled that the results stemming from the hydrodynamic theory postulating a lubrication-like (soft) contact of the macroion molecules with the sensor adequately reflect the adsorption kinetics. The range of validity of the intuitively used Sauerbrey model was also estimated. It was argued that acquired results can be exploited to control macroion adsorption at solid/liquid interfaces. This is essential for the optimum preparation of their supporting layers used for bioparticle immobilization and shell formation at nanocapsules in targeted drug delivery.

Pd-based membranes have a great potential for efficient production of pure hydrogen, enabling effective small-scale hydrogen production. Co-adsorption of gas phase species, mainly CO, is known to significantly limit the hydrogen flux through these expensive membranes. In this study, we employ a multi-scale modeling approach to investigate the impact of an applied electric field (AEF) on Pd-based membrane separators and reactors. We estimate the molecular-scale adsorption energies of CO and hydrogen on the Pd surface under AEF using DFT calculations. These are then used in unit-scale simulations of Pd-membrane separators and reactors. DFT simulations revealed that the AEF significantly changes the adsorption energy of CO due to its polarity, while unaffecting the nonpolar H2. A negative electric field of -1 V/Å reduces the adsorption energy of CO by 0.26 eV. Conversely, a positive field increases the adsorption energy of CO, resulting in a negative impact on the hydrogen flux. In a simple separator we found that a negative electric field of -1 V/Å significantly decreases the CO surface coverage (by up to 64 %) and increases the trans-membrane hydrogen flux by 2.5 times in some cases. In modeling a membrane reactor, we considered the impacts of the AEF on both competitive adsorption and equilibrium conversion. Ignoring the impact on equilibrium conversion, the model predicts a significant improvement in conversion of methane through steam reforming at 550 ◦C, from 35 % to 70 %. However, we calculate that the electric field significantly reduces the equilibrium conversion of the steam reforming reactions. It is thus desired to design a system in which the electric field is strong only close to the membrane surface.

Anion-exchange membrane (AEM) water electrolyzers (AEMWEs) have gained significant attention for their ability to utilize precious-metal-free catalysts and environmentally friendly fluorine-free hydrocarbon polymeric membranes. In this study, we identify and quantify the sources of performance losses in operando AEMWEs using an innovative approach based on electrochemical impedance spectroscopy and MATLAB-based impedance spectroscopy genetic programming. Using this approach, we move beyond conventional equivalent circuit models to develop a proper and analytical model of the distribution function of relaxation times (DFRT), enabling a deeper analysis of Faradaic and non-Faradaic processes. We apply this framework to isolate the critical processes─ohmic, ionic transport, charge transfer, and mass transfer─across various conditions, including KOH concentration, dry cathode operation mode with different anode electrolytes (KOH, K₂CO₃, and pure water), cell temperature, and membrane type. Our results indicate a considerable performance reduction as the KOH concentration in the anode decreases, primarily due to the relatively high ionic transport resistance. Our observations show that the performance of dry cathode operation with KOH in the anode yields a comparable performance to dual-side electrolyte feeding due to sufficient water back-diffusion from the anode, which efficiently maintains cathode hydration. Conversely, using pure water as an electrolyte in the anode with a dry cathode significantly increases cell resistances and compromises ionic transport, underscoring the urgent need for highly conductive ionomeric materials and strategies. These insights indicate that using DFRT to evaluate the AEMWE operation by separating and associating the electrochemical phenomena could simplify system design while enabling more efficient generation of dry, pure hydrogen and advancing the technology toward commercial application.