A method is developed for obtaining anisotropic composites based on the sulfonated cation-exchange MF-4SK and MK-40 membranes and the electroactive polymer polyaniline (PANI). The kinetics of aniline polymerization by successive diffusion in these membranes is investigated, and differences in the transport characteristics of the resulting MF-4SK/PANI and MK-40/PANI composites are identified. It is established from results of electroosmotic and diffusion experiments that the composite MF-4SK/PANI-1 membrane (after 1 h of aniline polymerization) suppresses electrolyte and water flow the most. Diffusion permeability drops by an order of magnitude, and water transport numbers are reduced by 50–70%. In the process of sodium chloride concentration by electrodialysis, the salt content of the concentrate increases by 50–70% with the composite MF-4SK/PANI-1 membrane compared to the base MF-4SK membrane and by 15–20% compared to the electrodialysis MK-40 membrane. Transport characteristics of the membrane pairs under investigation are calculated from the model of limiting concentration by electrodialysis: current efficiency, water transport numbers, osmotic and diffusion permeability. The dominant influence of the electroosmotic mechanism of water transport on the effect of salt solution concentration is established.

The method of template synthesis is used for the surface modification of MF-4SK membranes with polyaniline. The influence of the time of polyaniline synthesis in the surface layer of a perfluorinated...

An express method of synthesis of surface-modified membrane composites is suggested that allows obtaining heterogeneous materials featuring effects of the blocking of the transport of solvent ions and molecules. Studies using the methods of atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and IR spectroscopy show that polyaniline is in the form of emeraldine and water at the interface of polyaniline aromatic chains and initial membrane sulfogroups is in a structured state due to formation of interpolymer complexes. This determines higher thermal stability of composites and specific morphology of the polyaniline layer. Measurement of electroosmotic and diffusion permeability and also membrane conductivity in HCl solutions (with the concentration of 0.01 to 2 M) shows the blocking effect of the polyaniline layer causing a significant decrease in transport characteristics in a wide range of concentrations of equilibrium solutions. A model of structural heterogeneity of composites is offered that takes into account the presence of an additional structural element, polyaniline, in the basic polymer matrix. Mechanisms of the observed barrier effects are discussed. Comparison of the transport-structural parameters of the MF-4SK membrane and MF-4SK/PAn composites allows elucidating the role of polyaniline in formation of transport routes for ion and solvent fluxes.