Polyelectrolyte multilayers (PEMUs) are thin films prepared using the layer by layer deposition of oppositely charged polymers on a substrate. The use of these films as membranes provides several advantages such as good ion selectivity and high ionic fluxes. Despite studies of diffusion coefficients and ion transport inside multilayer membranes, little research has been done on the temperature dependence of PEMU permeability to cations and anions. Moreover, the performance has not been evaluated as a function of the stoichiometry of these films. Here, the temperature dependence ion transport of two electrochemically active species, potassium ferricyanide and ruthenium hexaamine, through a stoichiometric multilayer made from poly (diallyldimethyammonium) (PDADMA) and polystyrene sulfonate (PSS) is reported. The study uses cyclic voltammetry measurements at a rotating platinum disk electrode of a stoichiometric thin film as a function of temperature to show an evidence for a glass transition and obtain more information about the PEMU mechanical properties. It also explores the effect of using oppositely charged probes, as well as probe concentration on glass transition temperature. The results are compared to analogous measurements using dynamic mechanical testing, thus allowing for accurate prediction of a thermal transition based on a new parameter.

Ion transport in polyelectrolyte multilayers through the glass transition

2019 Spring National Meeting

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