PREPARATION AND CHARACTERIZATION OF MEMBRANES WITH POSITIVELY CHARGEDMAIN-CHAIN FROM POLYETHYLENIMINE

A membrane, which has positively charged groups in the polymer main ch ain, was prepared from polyethylenimine by crosslinking and successive alkylation. Dibromoalkane was used as a crosslinking agent. The cross linked membrane was alkylated using methyl iodide under several condit ions. Elemental and ICP emission analyses were introduced to measure t he rates of alkylation and quaternization. From the membrane potential measurement, the effective charge density was estimated. The highest value was about 1.0 M, which was obtained by a prolonged alkylation ti me. This value was larger than that of some commercial ion exchange me mbranes. The effective charge density, which was obtained by the last alkylation procedure, was 10 times larger than that of the former one, though the rate of quaternizing increased by less than a factor of tw o. This implies that the activity constant in the membrane increased w hen the charge density is increased.