6-Methacrylamidohexanoic acid

The improvement of enzyme like MIP is currently another area of intense research. Beside the use of the MIP themselves as catalysts, they may also be applied as enhancer of product yield in bio-transformation processes. In an exemplary condensation of Z-L-aspartic acid with L-phenylalanine methyl ester to Z-aspartame, the enzyme thermolysin was used as catalyst. In order to shift the equilibrium towards product formation, a product imprinted MIP was added. By adsorbing specifically the freshly generated product from the reaction mixture, the MIP helped to increase product formation by 40% [130]. MIP can also be used to support a physical process. Copolymers of 6-methacrylamidohexanoic acid and DVB generated in the presence of calcite were investigated with respect to promotion of the nucleation of calcite. Figure 19 (left) shows the polymer surface with imprints from the calcite crystals. When employing these polymers in an aqueous solution of Ca2+ and CO2 the enhanced formation of rhombohedral calcite crystals was observed see Fig. 19 (right) [131]. 

Crystals of calcium salts have also been used for imprinting polymers of carboxyhc acid functional monomers. Instances include imprinting artificial polymers with calcite to act as a template for the growth of specific crystal phases [95]. It has been reported that the calcite-imprinted polymers induced the formation of calcite nuclei even when the reaction conditions favored the growth of its other polymorph, namely aragonite. Another example of such work is the nucleation of calcium oxalate crystals on an imprinted polymer surface [96] where 6-methacrylamidohexanoic acid/divinylben-zene copolymers imprinted with calcium oxalate monohydrate (COM) or dihydrate (COD) crystals were used to foster the nucleation of CaOx crystals. The results revealed that the polymers gave rise to the formation of crystals that were the polymorphs of the template crystals. 

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