Self-organized films of supramolecular coordination polymers and their materials transport properties

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Coordinative layer-by-layer adsorption of metal ions and polymers with ligands as substituents (polytopic ligands) will be used to build up ultrathin films and separation membranes of coordination polymer networks and to study their materials transport properties. Up to now there is little knowledge about the use of coordination polymers as separation membranes. Starting point of the work will be the synthesis of suitable polymers with ligands as substituents (polytopic ligands) The preparation will be carried out as radical copolymerization of vinyl- and acrylic monomers, one of the comonomers (A) containing a ligand group. The other comonomer (B) will be varied such that copolymers with different hydrophilic properties, charge, and pH-, temperature- or potential-sensitive behaviour are formed.The deposited films will be investigated on their structural properties (optical absorption, film thickness, morphology, metal content). The membranes will be prepared upon layer-by-layer adsorption of various copolymers and metal salts on porous substrates. The network density of the membranes is varied by changing the comonomer ratio A:B of the copolymer. The materials transport will be investigated by measuring the permeation rates of salts and neutral molecules in aqueous and organic solution under conditions of diffusion dialysis and nanofiltration. Membranes of different network density will be studied. Membranes containing polymers with cationic or anionic comonomer units should be able to act as cation or anion exchangers. This will be proven studying the example of desalination and deacidification of aqueous electrolyte solutions under electrodialysis conditions. The possibility to prepare switchable membranes will also be studied. For this purpose membranes containing copolymers with redox-active components or pH- and temperature-sensitive sequences will be studied. For these membranes it will be tried to influence their flux and selectivity by changing the state of oxidation, the pH or the temperature.