Molecular‐imprinted nylon membranes for the permselective binding of phenylalanine as optical‐resolution membrane adsorbents

Nylon 6, nylon 6,6, and terephthalic phenylene polyamide (TPPP) were functionalized by phase‐inversion molecular imprinting to add L ‐phenylalanine recognition ability. Formic acid containing 20 wt % nylon and 8 wt % L ‐phenylalanine was used as the solvent for the cast solution of the imprinting process. The resultant porous membranes behaved as membrane adsorbents that separated the L / D mixture of the substrate. The imprinted nylon 6 and nylon 6,6 presented high selectivity to the L ‐form substrate with respect to the TPPP membranes, but the imprinted TPPP membranes showed higher binding capacity with 0.57 μmol/g for L ‐phenylalanine. The apparent partition coefficients of L ‐ and D ‐forms by the imprinted membranes were 6.8, 4.2, and 1.7 for nylon 6, nylon 6,6, and TPPP, respectively. The separation manner of the L ‐ and D ‐forms from the mixture was also confirmed by membrane filtration under 1.5 kgf/cm 2 of applied pressure. The imprinted nylon 6, nylon 6,6, and TPPP membranes had separation factors of L ‐ and D ‐phenylalanines of 1.1, 1.1, and 1.2, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 620–626, 2005