NAMS 2002 Workshop - ICOM 2008

introduction of methyl groups into the main chain polyamide component was
carried out, in which a new macromonomer, 3,5-bis(4-amino-3-
methylphenoxy)benzyloxypropyl- terminated polydimethylsiloxane (BAMPB-
PDMS) was synthesized instead of BAPB- PDMS. Generally, it has been known
that the introduction of alkyl group into aromatic polyamides could achieve the
improvement of their solubility. The polycondensation of BAMPB-PDMS with
terephthaloyl chloride yielded the desired siloxane-grafted polyamide
copolymers, MPA-g-PDMS. The copolymer membranes were prepared by
solvent casting method, and the gas permeability and pervaporation property of
these membranes were evaluated. PA-g-PDMS was insoluble in any solvents
after the copolymer was dried in vacuo, however, MPA-g-PDMS was soluble in
solvents, such as tetrahydrofuran, chloroform and dichloromethane, even after it
was completely dried. Therefore, MPA-g- PDMS exhibited the higher
processability than PA-g-PDMS. Then, the measurement of stress-strain
behavior of copolymer membranes was carried out, and these copolymer
membranes showed the high mechanical strength. The gas permeability property
of PA-g-PDMS and MPA-g-PDMS membranes was as same as that of the PDMS
cross-linking membrane for all of the gases. In addition, gas permeability of these
membranes were increased as increase of PDMS segment length, and these
values of MPA-g-PDMS were slightly higher than those of PA- g-PDMS
containing the same PDMS segment length. From the results of pervaporation of
the dilute aqueous solutions of organic solvents, it was found that both of PA-g-
PDMS and MPA-g- PDMS exhibited the excellent permselectivity toward several
organic solvents, such as alcohols, acetone, tetrahydrofuran, chloroform,
dichloromethane and benzene with a high and stable permeation. Such a high
selectivity for organic liquids would be due to the hydrophobic surface covered
with PDMS segments and the high permeability of the PDMS continuous domain,
which were confirmed by transmission electron macrography (TEM). Therefore, it
is expected that MPA-g-PDMS membranes can be used effectively for the
removal of organic solvents from their aqueous mixtures due to their properties of
high mechanical strength, durability and processability.