SYNTHESIS OF POLY(2,5-PYRIDINEDICARBOXYLIC ACID-ALT-HYDRAZINE) AND REVERSE-OSMOSIS PERFORMANCE OF ITS MEMBRANES

In the preparation of the title polymer by interfacial polycondensation the two reaction routes were studied and compared with respect to yield and polymer viscosity. The reaction conditions of the more readily accessible route involving the reaction of 2,5-pyridinedicarboxylic acid chloride with hydrazine was investigated in some detail. The polycondensate was fabricated into a reverse osmosis membrane by crosslinking reinforcement. Two attempts were made to improve water permeability: blending a more hydrophilic polymer, poly(4-vinylpyridine) and addition of an inorganic salt to the casting solution. Addition of the proper amount of lithium nitrate or a small amount of magnesium perchlorate was most effective for the improvement without considerable decrease in the membrane strength. The effect of the kind of the salt and addition ratio on the performance was discussed on the difference in the structure of polyhydrazides.