Uniform Molecular Imprinted Polymer by Precipitation Polymerization

초록

The technique of molecular imprinting consists of the self-assembly of a functional monomer and a template molecule in solution followed by the co-polymerization of the functional monomer and an excess of an appropriate crosslingking monomer. After dissolution of the small molecule, the resulting network polymer exhibits a significantly higher affinity for the molecule used as the template than for similar molecules, including closely related isomers. Molecular imprinted polymer (MIP) has been applied to chiral separation, solid extraction, biomimic sensor and membrane separation. The most successful non-covalent imprinting systems are based on commodity methacrylic monomers, such as methacrylic acid(MAA) because its carboxyl group is the most commonly hydrogen-bonding and acidic functional group in molecular imprinting, cross-linked with ethyleneglycol dimethacrylate(EDMA). Generally, MIPs are prepared in the from of a macroporous monolith that is then ground, sieved and floated in solvent to obtain the approporate particle sizes. The grinding, sieving and floating process is time-consuming and low yield producing. Further, the MIPs particles obtained by this way are irregular in shape and show a wide size distribution. This is the main reason that although the selectivity is usually high, MIPs are generally associated with a poor chromatographic efficiency and the elution of broad and asymmetric peaks. Uniformly sized and monodispersed particles, which was reported to be suitable as HPLC packing materials has been made by suspension polymerization and seed polymerization or multi-step swelling process. The limits of the above methods are either requiring use of special dispersing phases/surfactants or too complicated. Precipitation polymerization method, which was high in yield, easy to handle and showed specific binding sites to the target molecules, for preparing uniform MIPs microspheres has been reported.