Preparation of polyelectrolyte multilayer films consisting of sulfonated poly (ether ether ketone) alternating with selected anionic layers

We have developed a new approach involving the use of pressure during the alternating physisorption of oppositely charged polyelectrolytes on porous supports. For example, new polyelectrolyte multilayers (PEMs) as selective skins in composite membranes for NF were prepared by alternating layer-by-layer deposition of sulfonated poly (ether ether ketone) (sPEEK) and branched polyethyleneimine (PEI). During this electrostatic self-assembly deposition, it was demonstrated that the use of pressure could increase the salt rejection of the PEMs by one to two times. The effect of polymer charge density on membrane performance, e.g. sulfonation degree of sPEEK, was also studied. By depositing the sPEEK dissolved in methanol and branched PEI dissolved in water, the rejection of the PEMs could be further increased. The rejection is about 89% and very close to that of current commercially successful polyamide membranes, which is about 96%. The antifouling property of the PEMs has also been studied. Our membranes have a better antifouling property in comparison with commercial membranes, NTR 7450.