Ionic polymers form structures interfaces where both hydrophilic and hydrophobic segment co-exist. These types of materials are currently used as selective transport membranes ranging from electrolytic membranes and water purification ones, to drug delivery capsules where the nature of the solvent depends on the specific application.  To advance the current state of the art to responsive transport, the mechanism of diffusion across dynamic interfaces has to be resolved. In other words, the transport as the chemical composition and the topology of the interfaces are changed as transport takes place has to be elucidated. Here using in situ neutron reflectometry we study the transport of a series of alcohols across an interface of thin of a sulfonated polyphenylene based ionomers, whose highly rigid backbone distinguishes it from it from flexible polymers.  The films were exposed to alcohols with varying chain lengths and the reflectometry patterns were recorded as a function of time.  We will present the results for different sulfonation levels of the ionomer. At early stages the diffusion was characterized by a linear t� mass uptake that crossed over to a slower uptake at later times.  Interfacial effects dominate the onset of diffusion resulting in significant slower diffusion in comparison with the bulk polymer.  The effects of the hydrophobicity of the alcohols will be discussed following by comparison with the diffusion of water.  A scehmatic representaion of teh overall proccess is shown in Figure 1  .

Alcohols dynamics at the interface with thin structured ionomer films as derived from neutron reflectometry

248th National Meeting (2014)

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