(The) effect of additive on the formation of the polymer membrane

Abstract

In the preparation of ultrafiltration membrane, the effect of the addition of $ZnCl_2$in a casting solution, polysulfone (PSf)/N-methylpyrrolidone (NMP) solution was investigated on the membrane performance. PSf is an uncharged polymer, but PSf/NMP with $ZnCl_2$ showed an electroviscous behavior. The addition of 3 wt\% $ZnCl_2$ to PSf induced red shift of $3 cm^{-1}$ in $1152.2 cm^{-1}$ peak which was assigned to a symmetric vibrational stretching because of $ZnCl_2$ interacted with PSf chain. The addition of $ZnCl_2$ increased the reduced viscosity and decreased the critical concentration, resulting from the association between extended chains. The PSf/NMP solution with $ZnCl_2$ required less water for the precipitation point than saltless solution did. It was observed that the addition of $ZnCl_2$ increased the rejection rate and lowered the molecular weight cut-off (MWCO) of PSf membrane. A semi-interpenetrating network has been prepared for a polymer membrane. The first network consists of sodium alginate which provides the crosslinked network. The other is polyacrylic acid or polyacrylamide which imparts its characteristic into the polymer network. Using atomic acsorption spectroscopy, it was observed that the swelling of polymer membrane could be regulated by the control of theconcentration of calcium ion. Two types of solutes were used for membrane permeation. In the case of hydrocortisone used as a hydrophilic solute, permeation pattern was closely related to the swelling behavior of the polymer membrane. However, permeation of indomethacin used as a hydrophobic solute wasinfluenced by the intermolecular interaction in the polymer membranecharacterized by the FT-IR spectroscopy.