Porogen formulations for obtaining molecularly imprinted polymers with optimized binding properties

This paper examines the formulation of new porogenic mixtures used to prepare molecularly imprinted polymers (MIPs) in both thin film and bulk monolith formats. Films were cast by using spin coating to spread a pre-polymerization mixture onto a substrate, and rapid curing of the films was achieved with UV photolysis. The use of a low volatility solvent in combination with a linear polymer porogen resulted in a porous morphology and a 60-fold enhancement in the binding capacity, relative to a non-porous film prepared with a highly volatile solvent and in the absence of the polymer porogen. The opposite effect was seen in MIPs that were prepared in the traditional bulk monolith format, for which the binding efficiency of the MIP decreased monotonically with the concentration of the linear polymer porogen. Furthermore, bulk MIPs that were prepared in the presence of linear polymer porogens exhibited significantly decreased specific surface areas (from 620 to 8 m2/g for samples prepared with pure solvent and 50% polymer porogen, respectively). Despite the change in binding capacity and morphology, the selectivity of the bulk MIPs remained unaffected by the presence of the polymer porogens (approximately 50% chiral selectivity for all bulk MIPs considered). This difference in behavior of the two systems was attributed to the large difference in the kinetics of polymerization.