J. Nagaya et al., PREPARATION AND CHARACTERIZATION OF MEMBRANES WITH POSITIVELY CHARGEDMAIN-CHAIN FROM POLYETHYLENIMINE, Journal of applied polymer science, 48(8), 1993, pp. 1441-1447
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.