Properties of Nafion Under Uniaxial Loading at Different Temperatures: A Molecular Dynamics Study

Abstract

Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under uniaxial loading over a wide range of temperatures. According to the simulation results, increase of the temperature reduces the yield stress. The results also show that the polymer chains ordering increases the glass transition temperature and enhances the self-diffusion coefficient of water in hydrated Nafion. Comparisons show that the elastic modulus and viscosity coefficient obtained from the simulations at different temperatures are qualitatively in agreement with the measured values from experiments.

Mechanical behavior of a hydrated perfluorosulfonic acid membrane at meso and nano scales

“…19,20 In the current research realm, MD simulation has successfully applied to study the physicochemical properties of polymers, including structural, transport, and mechanical properties. [21][22][23][24][25][26][27] Some earlier studies [28][29][30][31][32][33] have reported the applications of MD simulation on PFSA membranes. Allahyarov and Taylor investigated the effects of stretching-induced structure orientation on proton conductivity and revealed that uniaxial stretching caused the elongation of hydrophilic regions along the stretching direction.…”

Molecular Dynamics Study on the Mechanical Deformation of Hydrated Perfluorosulfonic Acid Polymer Membranes

“…Ozmaian and Naghdabadi employed AA-MD simulations to investigate the behavior of a uniaxially deformed Nafion membrane under different applied loads and temperatures. 50 This study demonstrated that elongation of the polymer chains and crystallization of the material due to the applied uniaxial stress increases the glass transition temperature and enhances the water diffusivity of the hydrated membrane. However, no atomistic MD study has been reported that directly explores structural variations in PFSA membranes when deformed.…”

“…In this context, the diffusions of water and hydronium ions were found to increase following deformation. Ozmaian and Naghdabadi employed AA-MD simulations to investigate the behavior of a uniaxially deformed Nafion membrane under different applied loads and temperatures . This study demonstrated that elongation of the polymer chains and crystallization of the material due to the applied uniaxial stress increases the glass transition temperature and enhances the water diffusivity of the hydrated membrane.…”

Coarse-Grained Molecular Dynamics Simulation of Perfluorosulfonic Acid Polymer in Water–Ethanol Mixtures

“…Computational simulations have been widely used to investigate various characteristics of hydrated PFSA membranes, including proton and gas transportations, − membrane morphologies, − and mechanical deformations. − In addition, phase separations of ionomers in water–methanol mixtures have been investigated . However, only a few studies have analyzed the self-assembly of PFSA ionomers in dilute solutions using atomistic and coarse-grained (CG) molecular dynamics (MD) simulations. − Ghelichi et al evaluated the conformational changes of hypothetical charged polymers in solutions using CG–MD simulations based on an implicit solvent approach .…”