Preparation And Evaluation Of Molecularly Imprinted Monolithic Column By Living/Controlling Radical Polymerization Methods

Molecularly imprinted polymers (MIPs) are new technique for synthesizing the stationary phase with the ability of pre-selectivity and monolithic column is is a new type of chromatographic stationary phases. The combination of monolithic column and MIPs will play to their strengths. Living/Controlling radical polymerization techniques and their ability to improve the morphology of crosslinked polymer networks by controlling polymer chain growth, to resolve the heterogeneity in network morphology by free-radical polymerization, to enhance the binding affinities of imprinted polymers are reviewed. Synthesized of imprinted monolithic columns with different living/controlling radical polymerization methods, and different synthesize conditions, chromatographic conditions and the characteristic of MIP columns were systematically investigated. The results as follows:1Molecular crowding is a new approach to promoting molecular imprinting more efficiently. In this work, this concept was applied to the preparation of ibuprofen imprinted polymers monolithic with atom transfer radical polymerization (ATRP) for improving molecular recognition. An imprinted monolithic column was synthesized using a mixture of ibuprofen (template), anhydrous copper (Ⅱ) chloride, N, N, N’, N", N"-pentamthyldiethylenetriamine (the reverse ATRP reagents),4-vinylpyridine, ethylene glycol dimethacrylate, and polystyrene (molecular crowding agent). Some polymerization factors, such as template-monomer molar ratio, the composition of the reverse ATRP reagents and crosslinking density, on the imprinting effect of resulting MIP monolith were systematically investigated. The results indicated that the imprinted monolithic columns prepared with atom transfer radical polymerization retained higher imprinting factor for template than that prepared with traditional free radical polymerization method. The results suggested that atom transfer radical polymerization could enhance the binding affinities of imprinted polymers monolithic by improving the morphology of crosslinked polymer networks.2In this work, ionic liquids were firstly used as porogens to prepare carprofen MIPs monolith by reversible addition-fragmentation chain transfer (RAFT) polymerization. Separation of carprofen and its analogues can be achieved in5min with the imprinted monolithic column due to high column efficiency (up to12070plates/m) and good column permeability. Some polymerization factors, such as template-monomer molar ratio, the degree of crosslinking, the composition of the porogen and the content of CTA, on the column efficiency and imprinting effect of the resulting MIP monolith were systematically investigated. The optimal conditions for preparing the imprinted monolithic column were that the molar ratio of the template and functional monomer and cross-linking monomer was1:10:50, the mass ratio of chain transfer agent (CTA) and AIBN was3.7:1and the proportion of ionic liquids in the porogen was63%. The results of scanning electron microscopy and mercury intrusion analysis proved that the chain transfer agent be attributed to the increase in the uniform pore diameter and homogeneous network structures, which was also resulted in the increasing of column permeability and imprinting factor. The results suggested that the reversible addition-fragmentation chain transfer polymerization was an effective means to improve the molecular imprinted polymers properties.