Patent ID: 8066799
Filing Date: 2011-11-29
Classification: C08G,D01D,D01F

Abstract:
1. A method of making a crosslinked membrane, comprising: (a) preparing a polyimide polymer comprising carboxylic acid functional groups from a reaction solution comprising monomers and at least one solvent; (b) treating the polyimide polymer with a diol at esterification conditions in the presence of dehydrating conditions to form a monoesterified polyimide polymer; and (c) subjecting the monoesterified polyimide polymer to transesterification conditions to form a crosslinked membrane, wherein the dehydrating conditions at least partially remove water produced during step (b), and with the concentration of water in a solution comprising the polyimide polymer and the diol in step (b) maintained at between about 0 weight % and 0.08 weight %.