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 polycondensatio n the two reaction routes were studied and compared with respect to yi eld and polymer viscosity. The reaction conditions of the more readily accessible route involving the reaction of 2,5-pyridinedicarboxylic a cid chloride with hydrazine was investigated in some detail. The polyc ondensate was fabricated into a reverse osmosis membrane by crosslinki ng reinforcement. Two attempts were made to improve water permeability : blending a more hydrophilic polymer, poly(4-vinylpyridine) and addit ion of an inorganic salt to the casting solution. Addition of the prop er amount of lithium nitrate or a small amount of magnesium perchlorat e was most effective for the improvement without considerable decrease in the membrane strength. The effect of the kind of the salt and addi tion ratio on the performance was discussed on the difference in the s tructure of polyhydrazides.