Molecular Modeling of Nafion Permselective Membranes
Abstract
Specific goals: a) development of the versatile simulation tool to study morphology and transport in swollen polyelectrolyte membranes (PEM) of Nafion type at mesoscale (>20nm); b) understanding of the mechanisms of sorption and transport of chemical agents in swollen PEM. We developed molecular models for Nafion and nerve agent simulant DMMP and explored microphase segregation and mechanisms of DMMP sorption and transport in hydrated membranes with K+ counterion. It was shown that in dry membranes DMMP partly dissolves in the polymer. However, in the excess of water, DMMP neither mixes with aqueous subphase nor dissolves within the polymer subphase; DMMP forms clusters at the interface. Via a series of molecular dynamics simulation, we parameterized a coarse-grained model of Nafion and performed a series of dissipative particle dynamics simulations of microphase segregation in hydrated membranes with different water content. With the increase of the water content we found a percolation-type transition at about 6 wt% from the system of isolated hydrophilic clusters to the three dimensional network of irregular channels forming a hydrophilic subphase. A random walk model was developed for DMMP diffusion in hydrated polymer including volume and surface mechanisms. Simulation results correlate with experimental studies at US Army RDECOM.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 2005
- Accession Number
- ADA431689
Entities
People
- Aleksey M. Vishnyakov
- Alexander V. Neimark