Large Language Models as Molecular Design Engines.

The design of small molecules is crucial for technological applications ranging from drug discovery to energy storage. Due to the vast design space available to modern synthetic chemistry, the community has increasingly sought to use data-driven and machine learning approaches to navigate this space. Although generative machine learning methods have recently shown potential for computational molecular design, their use is hindered by complex training procedures, and they often fail to generate valid and unique molecules.

Thin-Film Composite Membranes for Hydrogen Evolution with a Saline Catholyte Water Feed.

Hydrogen gas evolution using an impure or saline water feed is a promising strategy to reduce overall energy consumption and investment costs for on-site, large-scale production using renewable energy sources. The chlorine evolution reaction is one of the biggest concerns in hydrogen evolution with impure water feeds. The "alkaline design criterion" in impure water electrolysis was examined here because water oxidation catalysts can exhibit a larger kinetic overpotential without interfering chlorine chemistry under alkaline conditions.

Improving the efficiency of CO electrolysis by using a bipolar membrane with a weak-acid cation exchange layer.

The efficient conversion of electricity to chemicals is needed to mitigate the intermittency of renewable energy sources. Driving these electrochemical conversions at useful rates requires not only fast electrode kinetics, but also rapid mass and ion transport. However, little is known about the effect of local environments on ionic flows in solid polymer electrolytes.

Fourier transform infrared spectroscopy investigation of water microenvironments in polyelectrolyte multilayers at varying temperatures.

Polyelectrolyte multilayers (PEMs) are thin films formed by the alternating deposition of oppositely charged polyelectrolytes. Water plays an important role in influencing the physical properties of PEMs, as it can act both as a plasticizer and swelling agent. However, the way in which water molecules distribute around and hydrate ion pairs has not been fully quantified with respect to both temperature and ionic strength.

Balancing Water Dissociation and Current Densities To Enable Sustainable Hydrogen Production with Bipolar Membranes in Microbial Electrolysis Cells.

Hydrogen production using two-chamber microbial electrolysis cells (MECs) is usually adversely impacted by a rapid rise in catholyte pH because of proton consumption for the hydrogen evolution reaction. While using a bipolar membrane (BPM) will maintain a more constant electrolyte pH, the large voltage loss across this membrane reduces performance. To overcome these limitations, we used an acidic catholyte to compensate for the potential loss incurred by using a BPM.

Solvent-non-solvent rapid-injection for preparing nanostructured materials from micelles to hydrogels.

Due to their distinctive molecular architecture, ABA triblock copolymers will undergo specific self-assembly processes into various nanostructures upon introduction into a B-block selective solvent. Although much of the focus in ABA triblock copolymer self-assembly has been on equilibrium nanostructures, little attention has been paid to the guiding principles of nanostructure formation during non-equilibrium processing conditions. Here we report a universal and quantitative method for fabricating and controlling ABA triblock copolymer hierarchical structures using solvent-non-solvent rapid-injection processing.

Anion Exchange Membranes with Dynamic Redox-Responsive Properties.

Redox-responsive anion exchange membranes were developed using photoinitiated free-radical polymerization and reversible oxidation and reduction of viologen. The membranes were formulated using poly(ethylene glycol diacrylate) and diurethane dimethacrylate oligomers, dipentaerythritol penta-/hexa-acrylate cross-linker, photoinitiators, and 4-vinylbenzyl chloride as precursors for functionalization. In the membrane, 4,4'-bipyridine reacted with the 4-vinylbenzyl chloride residues, and subsequently, unreacted amines were methylated with iodomethane to obtain viologen as both the ion carrier and redox-responsive group.

Biomimetic Separation of Transport and Matrix Functions in Lamellar Block Copolymer Channel-Based Membranes.

Cell membranes control mass, energy, and information flow to and from the cell. In the cell membrane a lipid bilayer serves as the barrier layer, with highly efficient molecular machines, membrane proteins, serving as the transport elements. In this way, highly specialized transport properties are achieved by these composite materials by segregating the matrix function from the transport function using different components.

Improved ATR-FTIR detection of hydrocarbons in water with semi-crystalline polyolefin coatings on ATR elements.

In situ measurement of hydrocarbons in water is critical for assuring the safety and quality of drinking water and in environmental remediation activities such as the cleanup of oil spills. Thus, effective detection methods of hydrocarbons in aqueous environments are important and several methods have been used for this type of sensing, including spectroscopic techniques, fiber optic sensors, and chromatography. However, under aqueous conditions, small amounts of hydrocarbons are difficult to detect due to their low concentration in water and robust sensing of these types of compounds in an aqueous environment remains a challenging analytical task.

Creating cross-linked lamellar block copolymer supporting layers for biomimetic membranes.

The long-standing goal in membrane development is creating materials with superior transport properties, including both high flux and high selectivity. These properties are common in biological membranes, and thus mimicking nature is a promising strategy towards improved membrane design. In previous studies, we have shown that artificial water channels can have excellent water transport abilities that are comparable to biological water channel proteins, aquaporins.

Thermodynamics of Counterion Release Is Critical for Anion Exchange Membrane Conductivity.

As the field of anion exchange membranes (AEMs) employs an increasing variety of cations, a critical understanding of cation properties must be obtained, especially as they relate to membrane ion conductivity. Here, to elucidate such properties, metal cation-based AEMs, featuring bis(norbornene) nickel, ruthenium, or cobalt complexes, were synthesized and characterized. In addition, isothermal titration calorimetry (ITC) was used to probe counterion exchange thermodynamics in order to understand previously reported differences in conductivity.

Resistance and Permselectivity of 3D-Printed Micropatterned Anion-Exchange Membranes.

It has been demonstrated that a micropatterned surface can decrease the resistance of anion-exchange membranes (AEMs) and can induce desirable flow properties in devices, such as mixing. Previously, a model that related the resistance of flat and patterned membranes with the same equivalent thickness was proposed, which used the patterned area and thickness ratio of the features to describe the membrane resistance. Here, we explored the validity of the parallel resistance model for a variety of membrane surface designs and area ratios.

Substrate-Dependent Physical Aging of Confined Nafion Thin Films.

The humidity-induced physical aging, or structural relaxation, of spin-cast Nafion thin films on gold, carbon, and native oxide silicon (n-SiO) substrates was examined using spectroscopic ellipsometry (SE). Physical aging rates, β, were calculated from the change in measured sample thickness, , upon exposure to controlled humidity. Three Nafion films, = 188, 57, and 27 nm, deposited on gold substrates demonstrated an increased β with decreasing thickness due to confinement.

Quantifying Carboxylic Acid Concentration in Model Polyamide Desalination Membranes via Fourier Transform Infrared Spectroscopy.

Carboxylic acid groups impart hydrophilicity and ionizable moieties to polyamide membranes for desalination, hence influencing water and ion transport through the material. Model polyamide films were synthesized via molecular layer-by-layer deposition on planar substrates to study the formation process of these materials and overcome the chemical and topological inhomogeneity inherent to conventional interfacially polymerized polyamide membranes. The carboxylic acid content in these model films was characterized using Fourier transform infrared (FTIR) spectroscopy by quantifying the C=O band at 1718 cm.

Multivariate analysis of attachment of biofouling organisms in response to material surface characteristics.

Multivariate analyses were used to investigate the influence of selected surface properties (Owens-Wendt surface energy and its dispersive and polar components, static water contact angle, conceptual sign of the surface charge, zeta potentials) on the attachment patterns of five biofouling organisms (Amphibalanus amphitrite, Amphibalanus improvisus, Bugula neritina, Ulva linza, and Navicula incerta) to better understand what surface properties drive attachment across multiple fouling organisms. A library of ten xerogel coatings and a glass standard provided a range of values for the selected surface properties to compare to biofouling attachment patterns. Results from the surface characterization and biological assays were analyzed separately and in combination using multivariate statistical methods.

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers.

The charge density and hydrogen bonding with water of five different polymer membranes functionalized with various sulfonate side-chain chemistries were investigated using Fourier transform infrared (FTIR) techniques and density functional theory (DFT) calculations. The peak position of the OD stretch of dilute HOD absorbed into the sulfonated poly(sulfone) membranes was studied using FTIR to compare the charge density of the sulfonate headgroup across the different samples, which can ultimately be related to the acidity of the proton-form sulfonate moieties. The OD peak was deconvoluted to determine the percentage of headgroup-associated, intermediate, and bulk water.

First-Principles Calculation of Pt Surface Energies in an Electrochemical Environment: Thermodynamic Driving Forces for Surface Faceting and Nanoparticle Reconstruction.

Platinum is a widely used catalyst in aqueous and electrochemical environments. The size and shape of Pt nanoparticles and the faceting (and roughness) of extended Pt surfaces change during use in these environments due to dissolution, growth, and reconstruction. Further, many Pt nanoparticle synthesis techniques are carried out in an aqueous environment.

Water Sorption in Electron-Beam Evaporated SiO on QCM Crystals and Its Influence on Polymer Thin Film Hydration Measurements.

Spectroscopic ellipsometry (SE) and quartz crystal microbalance (QCM) measurements are two critical characterization techniques routinely employed for hydration studies of polymer thin films. Water uptake by thin polymer films is an important area of study to investigate antifouling surfaces, to probe the swelling of thin water-containing ionomer films, and to conduct fundamental studies of polymer brush hydration and swelling. SiO-coated QCM crystals, employed as substrates in many of these hydration studies, show porosity in the thin electron-beam (e-beam) evaporated SiO layer.

Click Cross-Linking-Improved Waterborne Polymers for Environment-Friendly Coatings and Adhesives.

Waterborne polymers, including waterborne polyurethanes (WPU), polyester dispersions (PED), and polyacrylate emulsions (PAE), are employed as environmentally friendly water-based coatings and adhesives. An efficient, fast, stable, and safe cross-linking strategy is always desirable to impart waterborne polymers with improved mechanical properties and water/solvent/thermal and abrasion resistance. For the first time, click chemistry was introduced into waterborne polymer systems as a cross-linking strategy.

3D Printing of Micropatterned Anion Exchange Membranes.

Micropatterned anion exchange membranes (AEMs) have been 3D printed via a photoinitiated free radical polymerization and quaternization process. The photocurable formulation, consisting of diurethane dimethacrylate (DUDA), poly(ethylene glycol) diacrylate (PEGDA), dipentaerythritol penta-/hexa- acrylate, and 4-vinylbenzyl chloride (VBC), was directly cured into patterned films using a custom 3D photolithographic printing process similar to stereolithography. Measurements of water uptake, permselectivity, and ionic resistance were conducted on the quaternized poly(DUDA-co-PEGDA-co-VBC) sample series to determine their suitability as ion exchange membranes.

Highly conductive side chain block copolymer anion exchange membranes.

Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.

Increased Hydrogel Swelling Induced by Absorption of Small Molecules.

The water and small molecule uptake behavior of amphiphilic diacrylate terminated poly(dimethylsiloxane) (PDMSDA)/poly(ethylene glycol diacrylate) (PEGDA) cross-linked hydrogels were studied using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. These hydrogel networks absorbed more water as the PEGDA content of the network increased. In contrast to typical osmotic deswelling behavior that occurs when liquid water equilibrated hydrogels are immersed in small molecule solutions with water activities less than unity, water-swollen gels immersed in 2-acrylamido-2-methylpropanesulfonic acid (AMPS-H) solutions rapidly regained their water content within 4 min following an initial deswelling response.

Signal Enhanced FTIR Analysis of Alignment in NAFION Thin Films at SiO and Au Interfaces.

Spin-cast NAFION samples were prepared on silicon native oxide and gold substrates with film thicknesses ranging from 5 to 250 nm. The influence of NAFION film thickness on the infrared spectrum of the polymer was investigated in substrate overlayer attenuated total reflection (SO-ATR) geometry at incident angles between 60° and 65°. In the grazing angle SO-ATR geometry, the thickness of the film significantly affected the position and absorbance of characteristic peaks in the FTIR spectrum of NAFION.

Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities.

Separators are used to protect cathodes from biofouling and to avoid electrode short-circuiting, but they can adversely affect microbial fuel cell (MFC) performance. A spray method was used to apply a polyvinyl alcohol (PVA) separator to the cathode. Power densities were unaffected by the PVA separator (339±29mW/m(2)), compared to a control lacking a separator in a low conductivity solution (1mS/cm) similar to wastewater.

Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis.