Takuya Mabuchi

We have performed a detailed analysis of the structural properties of the sulfonate groups in terms of isolated and overlapped solvation shells in the nanostructure of hydrated Nafion membrane using classical molecular dynamics simulations. Our simulations have demonstrated the correlation between the two different areas in bound water region, i.e., the first solvation shell, and the vehicular transport of hydronium ions at different water contents. We have employed a model of the Nafion membran

A reactive molecular dynamics simulation has been performed for the characterization of the relationship between proton transport and water clustering in polymer electrolyte membranes. We have demonstrated that the anharmonic two-state empirical valence bond model is capable of describing efficiently excess proton transport through the Grotthuss hopping mechanism within the simplicity of the theoretical framework. To explore the long-time diffusion behavior in perfluorosulfonic acid membranes wi

Coarse-grained molecular dynamics simulations using explicit solvent models were performed to understand Nafion ionomer morphology in 1-propanol (NPA)/water solutions under various conditions (ionomer concentration, NPA/water fraction, and salt addition). The self-assembly behavior of ionomers into a cylindrical aggregate with a diameter of ∼2–3 nm was observed. At low ionomer concentration (≤5.0 wt %), the ionomer aggregate becomes smaller in size and thinner with increasing NPA fractions. At h

ABSTRACT The self‐assembly of Nafion ionomer in a mixture of 1‐propanol (NPA) and water was investigated using coarse‐grained molecular dynamics simulations. Ionomer formation into cylindrical bundle‐like aggregates is observed when the ionomer chain size is sufficiently large. The size of ionomer bundles decreases (the diameter decreased from ~2.5 to ~1.9 nm) with increasing NPA content, which indicates that the ionomers tend to be more dispersed at higher NPA content. The results of simulation

ABSTRACT The effects of water nanochannel diameter on proton transport pathways and properties have been studied using reactive molecular dynamics simulations. The proton distributions and diffusivities have been evaluated using the cylinder model of water domains at various diameters that is the most typical proposed morphological model in proton‐exchange membranes. The proton distributions are analyzed to clarify proton pathways by classifying the water channel into two regions in parallel: an

Coarse-grained molecular dynamics simulations were performed to understand the evolution of ionomer morphologies in solutions during solvent evaporation. To reproduce experimental fabrication conditions, the simulation conditions, such as evaporation and sedimentation rate, were determined based on a dimensionless parameter, the Péclet number, providing a direct link between simulation results and experimental findings. The effects of ionomer loading and substrate wettability on the morphologies

Molecular dynamics simulations are performed to investigate the nucleation and growth of cavities in a hydrated Nafion membrane under mechanical deformation. The simulation model used in this study accurately reproduces the experimental values of the elastic modulus of the membrane as a function of water content. The results obtained from triaxial tensile tests reveal a ductile to brittle transition as the water content increases. The nucleation and growth of the cavities have been quantitativel

Atomistic analysis of the ion transport in polymer electrolytes for all-solid-state Li-ion batteries was performed using molecular dynamics simulations to investigate the relationship between Li-ion transport and polymer morphology. Polyethylene oxide (PEO) and poly(diethylene oxide-alt-oxymethylene), P(2EO-MO), were used as the electrolyte materials, and the effects of salt concentrations and polymer types on the ion transport properties were explored. The size and number of LiTFSI clusters wer

A detailed analysis of the proton solvation structure and transport properties in aqueous solutions is performed using classical molecular dynamics simulations. A refined two-state empirical valence bond (aTS-EVB) method, which is based on the EVB model of Walbran and Kornyshev and the anharmonic water force field, is developed in order to describe efficiently excess proton transport via the Grotthuss mechanism. The new aTS-EVB model clearly satisfies the requirement for simpler and faster calcu

In this study, we performed reactive molecular dynamics simulations to characterize proton solvation and transport in concentrated hydrochloric acid solutions. The correlation contribution to the total proton mean square displacement is found to be negative for all acid concentrations, indicating the anticorrelation between the Grotthuss and vehicular diffusions. For the vehicular diffusion, the hydronium ions tend to move freely toward the lone pair side independent of acid concentrations, wher

Abstract A molecular dynamics simulation is performed to understand the effects of ferrous ion contaminations on the proton transport property and nanostructures of solvent molecules in hydrated Nafion membranes while considering the Grotthuss mechanism. At low hydration conditions, the proton diffusivity has a local maximum at a certain concentration of ferrous ions. In the case of low ferrous ion concentration (≈25% of total cation charge), proton diffusivity is similar to that in the pure mem

We have performed a detailed analysis of proton solvation and transport properties in hydrated Nafion using molecular dynamics simulation. The revised empirical valence bond (EVB) method was developed in order to treat the excess proton transport through the Grotthuss mechanism. The new EVB model predicts a significantly enhanced transport in comparison with previous hopping models as well as the classical hydronium diffusion, which largely improves the agreement with the available experimental

Effects of polymer structure on the electroosmosis in proton exchange membranes (PEMs) have been investigated using a reactive molecular dynamics simulation. An anharmonic two-state empirical valence bond (αTS-EVB) model has been used to describe efficiently excess proton transport via the Grotthuss hopping mechanism. The electroosmotic drag coefficients (i.e., the number of water molecules transferred through the membrane per proton) has been evaluated directly in PEMs consisting of various equ

We performed coarse-grained molecular dynamics simulations with the Martini3 force field to investigate elastin-like polypeptide (ELP) coacervate formation and its internal structural and dynamics properties. Coacervate formation was found to be enhanced with increasing polymer concentration and polymer length, whereas no significant changes in the structural and dynamic properties inside the coacervate phase were observed among coacervates with different polymer concentrations and polymer lengt