NAMS 2002 Workshop - ICOM 2008

Pervaporation and Vapor Permeation I – 6
Tuesday July 15, 11:30 AM-12:00 PM, Honolulu/Kahuku
Preparation of Asymmetric Polyetherimide Membranes for Molecular Liquid
Separations
A. El-Gendi, LSGC-CNRS, Nancy Université, France
D. Roizard, LSGC-CNRS, Nancy Université, France, Denis.Roizard@ensic.inpl-nancy.fr
E. Favre (Speaker), LSGC-CNRS, Nancy Université, France
The aromatic polyimides are a well-known class of polymer materials, which
have been widely studied for over 20 years in the field of membrane separation.
As glassy polymers, they possess remarkable mechanical and chemical
properties for organic materials, but in general their permeability coefficients are
limited because of their rigid carbon skeleton and low available free volume;
hence their application to molecular separation is limited to gas separations.
To circumvent this problem, and to broaden the scope of these very stable
polymers, we have studied the properties of a block-ether aromatic polyimide
series comprising a flexible block and we prepared asymmetrical films with the
aim of achieving liquid-liquid separations. Using various experimental conditions
of phase inversion, either totally opened microstructures typical of microfiltration
membranes or asymmetric microstructures with a thin dense top surface could
be obtained and then tested for the fractionation by pervaporation of model liquid
mixtures, such as toluene - heptane or water - ethanol. As an interesting
outcome, it was found that some copolyether-imide aromatic membranes could
indeed present high permeation fluxes and fairly good selectivities. Thus, it is
expected that the development of these new asymmetric block copolyimide
membranes might give rise to high performance membrane systems for
applications in liquid-liquid separations.