Preparation And Analytical Application Of Surface Molecularly Imprinted Polymer For Melamine Base On Silica Gel

Molecularly imprinted polymers prepared by molecular imprinting technique have attracted considerable interest in recent years due to their excellent affinity and selectivity as well as their high stability, and have a wide application prospect in many fields, such as solid phase extraction, biomimetic sensors, mimic enzyme, drug delivery and so on. Because of its accessible imprinted molecular recognition sites on the surface of polymers, which can quickly reach the adsorption saturation, imprinted polymer prepared by surface imprinting technique has aroused people's wide concern.In this paper, surface molecularly imprinted polymer was prepared by surface molecular imprinting technique base on silica gel, using melamine a concerned material as the template molecule,α-methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the crosslinker, azoisobutyronitrile as the initiator. First, interaction between functional monomer and template molecule was studied by UV-vis spectroscopic and 1HNMR analysis methods. Then, surface molecular imprinted polymers were synthesized base on two different modified silica surface, and their morphological structure and adsorption properties were studied using a variety of testing methods.Surface molecular imprinted polymers was further prepared after silica was modified using aminopropyl triethoxysilane as midifiers. The experiment was proved to be successful by infrared spectroscopy, thermal analysis and scanning electron microscopy analysis. The average pore diameter of the polymer on silica surface is 2.15 nm. With the maximum apparent adsorbance is 4.88 mg/g, which was got using Scatchard model, the imprinted polymer not only has better dynamics and specific identification, but also has a higher adsorption capacity for the template molecule. The polymer also has good stability and good practical value.The average pore diameter and maximum apparent adsorbance of surface molecular imprinted polymer is 0.824 nm and 5.81 mg/g, which was synthesized using vinylthiethoxy silane as modifier, The results show that the imprinted polymer has good adsorption properties for melamine and can reach binding equilibriums within 10min. Competitive adsorption experiment shows that silica surface imprinted polymer has specific identification of melamine. Using this silica imprinted polymer as solid phase extraction filler can selectively separate and enrich melamine in milk powder and milk, with average recovery rate are 90.2%,84.6% respectively.