Preparation And Performance Research Of The Photoresponsive Molecularly Imprinted Polymers-silica Microspheres

ABSTRACT:The conventional molecularly imprinted materials still have many problems, such as incomplete template removal, slow mass transfer and small binding capacity. A novel type of azobenzene-containing photo-responsive molecularly imprinted polymers (MIP)-silica microspheres was successfully developed to solve these problems.First, the azobenzene-containing complex was synthesized by using the Diazotization reaction, Nucleophilic substitution reaction, and Claisen Schmidt reaction. Then the azobenzene-containing complex was chemically bonded onto the surface of activated silica particles. MIP-silica microspheres were subsequently prepared through the graft co-polymerization process by using Ibuprofen, EGDMA, AIBN as the template, crosslinker, initiator, respectively. The SEM and DLS curves showed the MIP-silica microspheres were uniform and narrowly size distributed, and the diameters were approximately800nm.Second, some basic research was done to study the adsorption properties of the MIP-silica microspheres, including:adsorption kinetics, equilibrium binding experiments and selectivity experiments. The MIP-silica microspheres reached their binding equilibriums in about110min, the maximum adsorption capacity was35.6mg·g-1, and the selective adsorption capacity towards ibuprofen was about4times of the structurally compounds’under the visible light irradiation or in the dark. The results demonstrated that the imprinted silica microspheres possessed obvious molecular imprinting effects towards ibuprofen, rather fast template rebinding kinetics, and appreciate selectivity over structurally related compounds.Third, we focused on the study of the photo-Isomerization performances of the MIP-silica microspheres. The MIP-silica microspheres regularly released and retook template molecules with the365nm UV light and450nm visible light alternately irradiated. And the photo-isomerization process was reversible. This result demonstrated the novel MIP-silica microspheres could photo-regulate the release and uptake process of the template molecules.Finally, the template molecules elution rate increased from80%to92%when combined with the light irradiation. This result indicated the template molecules were almost completely eluted in molecularly imprinted polymer-silica microspheres.The prepared photoresponsive MIP-silica microspheres have stable mechanical properties, outstanding adsorption performance. Such photoresponsive MIP-silica microspheres should be of tremendous potential in many applications, such as smart separation, extraction, and assays, and drug delivery systems.