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Abstract:
To establish the application of Molecularly Imprinted Polymers (MIP's) as separation material in a continuous enantioseparation process we have developed a diffusion cell for polymeric membranes. Enantioseparation by crystallisation does not work with a racemic feed but gives enantiopure crystals when an enriched solution is used.This may be provided by enantioselective membrane separation. The first step we are currently working on is the production of a material that can recognise one of the two enantiomers of mandelic acid. The preparation of chiral membranes made of Molecularly Imprinted Polymers is done by radical polymerisation of a solution of the template (i.e. one of the enantiomers of mandelic acid), cross-linker and functional monomers, which build non-covalent complexes with the template. These complexes are frozen in during the polymerisation to give recognition sites after the extraction of the template. To induce a porous structure inside the MIP different porogenic mixtures of polar and nonpolar solvents are investigated. The porous structure depends on both the ratio of porogenic to monomeric mixture and the polarity of the solvent. Finally, after an extraction step in which the template, the porogen and non-reacted monomers are washed out, one obtains a porous monolith. Parallel the modelling of the membrane process supports the finding of the best properties for the membrane material and suitable operation parameters. First results both for preparation molecularly imprinted polymers and for modelling the membrane separation will be presented and discussed.
