Preparation of PVA-based charged mosaic membrane using screen-printed method and evaluation of ion transport properties

In this study, a polyvinyl alcohol (PVA)-based charged mosaic membrane (CMM) with a stripe-shaped charged structure from PVA-modified block copolymers was fabricated on a non-fabric support using a screen-printed method. The membrane structure of the stained CMM indicated that the striped negatively (N)- and positively (P)-charged layers with 20 m thickness were formed on the support. The domain sizes of the N and P layers were 173 and 203 m, respectively. Membrane potential measurements revealed that the charge density in the N layers of the fabricated CMM (CM-1) was almost the same as that in the P layers. A diffusion dialysis test indicated that the CM-1 had an electrolyte permselectivity of 986 between 0.1 M KCl and 0.1 M sucrose; a value which is approximately 20 times higher than that of Desalton® which is the only commercially available CMM. A water permeation test showed that CM-1 exhibited negative osmosis, which is a unique behavior of CMMs with high electrolyte permselectivity. Absolute flux in the negative osmosis was maximum when the electrolyte concentration was 0.1 M. A piezo dialysis test at an initial concentration of 500 ppm NaCl and applied pressure of 0.7 MPa, indicated that the rejection of CM-1 yielded negative value, confirming that the membrane can desalt salty water via piezo dialysis.