Membranes based on poly(gamma-methyl-L-glutamate): synthesis, characterization and use in chiral separations

A facile 'one-pot' synthesis for poly(gamma -methyl-L-glutamate) (PMLG) mem branes is reported. Despite having an alpha -helical secondary structure, a s demonstrated via IR, these membranes did not show enantioselective behavi or in pressure driven permeation of Trp. Therefore, the transesterification of PMLG with Igepal and Brij(R) 30 is introduced in a next step and the re sulting polymers are characterized by means of IR and NMR. Supported membra nes made from these materials show permselectivity towards D-Trp under a pr essure gradient, but the enantiomeric excess of the permeate phase declines as a function of time. In order to realize a constant enantioselectivity, electrodialysis is demonstrated to be a suitable membrane process. Moreover , the obtained permeation rates of Ac-Trp are among the best ever reported for solid enantioselective membranes and approximate those realized with li quid membranes. (C) 2001 Elsevier Science B.V. All rights reserved.