(739a) Dissipative Particle Dynamics Simulations of Anion Exchange Membranes

Anion exchange membrane (AEM) is composed of a polymer backbone tethered with ion exchange side chains, which transports ions and water within its nano-segregated hydrophilic domains while being hydrated. Studies of AEM in the past few decades show that AEM is a competitive alternative to conventional proton exchange membranes (PEM) in fuel cell (FC) application, mainly because of the alkaline environment allowing the use of non-noble metal for electro-catalysts.

Here, dissipative particle dynamics (DPD) simulation is used to explore the relation between the diffusivity of mobile components and mesoscopic structures of AEM in terms of different hydration levels, ion exchange capacities, and types of copolymers and functional groups. The provided fundamental information is useful for designing more versatile AEMFCs.

Previously devised strategies for studying PEM are transferred into this AEM work. Scale-bridging parameterization¹ determines the pairwise potential between coarse grained (CG) beads by mapping to bulk properties of the bead components. Neighbor and second-neighbor bonds¹ are used to regulate CG molecules in order to preserve their configurations on the atomistic level. Short-range Morse potential is used to mimic the transport mechanisms of anions and the association-dissociation equilibrium² between anions and the functional groups, along with their explicit electrostatic interactions. This methodology shows promising results on modeling proton conductivity in sPS³ and Nafion⁴, and its performance on modeling AEM will be discussed.

References

[1]M. T. Lee, R. F. Mao, A. Vishnyakov, and A. V. Neimark, J. Phys. Chem. B 120 (2016) 4980-4991.

[2]M. T. Lee, A. Vishnyakov, and A. V. Neimark, J. Chem. Theory Comput. 11 (2015) 4395-4403.

[3]M. T. Lee, A. Vishnyakov, and A. V. Neimark, J. Chem. Phys. 144, 014902 (2016)

[4]A. Vishnyakov, R. Mao, M. T. Lee, and A. V. Neimark, J. Chem. Phys. 148, 024108 (2018)