Transferable coarse-grained model for perfluorosulfonic acid polymer membranes

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Perfluorosulfonic acid (PFSA) membranes are crucial as proton exchange membranes in various applications.
• The aqueous domain structure within PFSA membranes directly impacts proton conductance.
• Existing coarse-grained (CG) models often lack chemical accuracy for realistic membrane morphology studies.

Purpose of the Study:

• To construct a predictive CG model for PFSA membrane structure and morphology.
• To ensure compatibility with the Sinoda-DeVane-Klein (SDK) CG water model.
• To achieve a chemically accurate CG model for molecular design and realistic membrane investigations.

Main Methods:

• Extended the parameter set for the SDK CG force field.
• Utilized experimental data and all-atom (AA) molecular dynamics (MD) simulations.
• Employed the iterative Boltzmann inversion (IBI) approach to refine structural properties, creating a hybrid SDK/IBI model.

Main Results:

• The hybrid SDK/IBI model demonstrated improved structural properties compared to the original SDK model.
• Radial distribution functions from the hybrid model showed better agreement with AA-MD simulations.
• The model accurately reproduced thermodynamic and structural properties of PFSA membranes across various water contents.

Conclusions:

• The developed hybrid SDK/IBI CG model offers a chemically accurate and predictive tool for PFSA membranes.
• The model shows good transferability and significant potential for simulating realistic long-chained PFSA membranes.
• This advancement facilitates concrete molecular design and deeper understanding of membrane morphology's role in proton transport.