Layer-by-Layer Assembly of Polyelectrolyte Chains and Nanoparticles on Nanoporous Substrates: Molecular Dynamics Simulations

We performed molecular dynamics simulations of a multilayered assembly of oppositely charged polyelectrolyte chains and nanoparticles on porous substrates with cylindrical pores. The film was constructed by the sequential adsorption of oppositely charged species in a layer-by-layer fashion from dilute solutions. The multilayer assembly proceeds through surface overcharging after the completion of each deposition step. The substrate overcharging fraction fluctuates around 0.5 for nanoparticle-polyelectrolyte systems and around 0.4 for polyelectrolyte-polyelectrolyte systems. The surface coverage increases linearly with the number of deposition steps. The rate of surface coverage increases as a function of the number of deposition step changes when the pore is blocked. The closing of the pore occurs from the pore entrance for nanoparticle polyelectrolyte systems. In the case of polyelectrolyte polyelectrolyte systems, the pore plug is formed inside the pore and then spreads toward the pore ends.