A New Type Of Core - Shell Development And Application Of Molecularly Imprinted Polymeric Material Research

In this paper, core-shell molecularly imprinted polymers （MIPs） based on silicaoxide or monodisperse hybrid silica microsphere were prepared by sol-gel or thermalpolymerization method with surface imprinting technique. And these polymers weresuccessfully used in the separation of food additive, natural product and racemates.1. A novel core-shell imprinted polymer based on the surface-modified silica gelwas prepared with sol-gel method successfully by using benzoyl peroxide as thetemplate molecule. The morphology and performance of the imprinted polymers werecharacterized by infrared spectroscopy, scanning electron microscopy andthermogravimetic analysis. The results showed that the polymers were evenlydistributed, good thermal stability,300nm of average diameter and the shell thicknessis about50nm. The adsorption performance was investigated by high-performanceliquid chromatography （HPLC）, and the results showed that the imprinted polymersexhibit specific sorption to benzoyl peroxide with selectivity coefficient of6.59; and theaverage recovery rate of94.98%by using solid-phase extraction experiments. Theimprinted polymers were applied to separate and enrich benzoyl peroxide from floursuccessfully.2. A core-shell complex-imprinted polymer （CIP） was synthesized and evaluatedfor selective extraction of melamine from dairy products. The CIP synthesis based onsurface modification of home-made silicon microspheres was conducted via a metalcomplex as functional monomer, ethylene glycol dimethylacrylate （EGDMA） ascross-link and melamine as template. The resulting CIP was characterized by scanningelectron microscopy （SEM） and Fourier transform infrared spectroscopy （FT-IR）. Whenthe molar ratio of copper （II） methacrylate （Cu（MAA）2） to EDGMA was1:10,well-distributed particles were obtained. The complex-imprinted solid-phase extraction（CI-SPE） condition was optimized and the maximum enrichment factor of melaminecan be up to40. The reliability of CI-SPE for extraction and enrichment of melaminewas investigated and proved by using spiked samples including milk and milk powderwith the recoveries ranging from87%to92%.3. Employing resveratrol as template molecule, acrylamide as functional monomerand ethyleneglycol dimethacrylate as cross-linkers, a core-shell resveratrol imprintedmicrospheres were prepared based on the surface of SiO₂with a surface imprintingtechnique. The molecularly imprinted microspheres were characterized by infraredspectroscopy （IR）, scanning electron microscopy （SEM） and thermogravimetic analysis,and the results showed that the surface grafting of molecularly imprinted polymer-shellparticles on SiO₂were successful; the particles were evenly distributed and exhibit goodthermal stability. High performance liquid chromatography was also used to investigate the imprinted microspheres adsorption performance, and the results showed that theimprinted microspheres exhibited good recognition performance. The maximumadsorption capacity are Qmax1=9.087mg/g and Qmax2=13.80mg/g by using the model ofScatchard analysis. The imprinted micospheres were applied to separate resveratrolfrom the extraction of rhizoma polygoni cuspidate successfully.4. A L-phenylalanine （L-Phe） imprinted polymer （MIP） based on monodispersehybrid silica microspheres （MH-SiO₂） with-CH=CH₂groups was synthesized bysurface imprinting technique. The MH-SiO₂was synthesized by a sol-gel process inaqueous media using tetraethylorthosilicate （TEOS） and3-methylacryloxypropyltrimethoxysilane （MATES） as the precursors. The morphologies of MH-SiO₂and MIPwere characterized with scanning electron microscope （SEM） and the imprinted shellthickness on the surface of MH-SiO₂was calculated as0.5μm. Compared with theimprinted polymer prepared only by β-cyclodextrin （β-CD） or methacrylic acid （MAA）as functional monomer, the imprinted polymer prepared with both β-CD and MAA asbinary functional monomers hold the highest adsorption capacity. Under the optimumchromatographic conditions, a complete baseline separation of phenylalanine racemateswas observed only using the column packed with the imprinted polymer prepared withboth β-CD and MAA as binary functional monomers. And the separation factor andresolution of the imprinted polymer towards phenylalanine racemates were calculated as1.41and1.46, respectively, which is higher than that of other imprinted polymers.