Preparation and characterization of photoresponsive organic-inorganic hybrid molecularly imprinted polymers

A photoresponsive functional azobenzene monomer containing silica was prepared by covalent imprinting for 2,4-dicholrophenoxyacetic acid(2,4-D) via oxidation-coupling reaction, acetylation and esterification reaction using commercially available p-nitrophenol, 2,4-dicholrophenoxyacetic acid and 3-chloropropyltriethoxysilane as the starting materials. Photoresponsive organic-inorganic hybrid molecular imprinted polymer(OIHMIP) for 2,4-D was prepared by sol-gel method. The photoresponsive properties, absorption abilities, selective recognition and photoregulated control the release and uptake of target molecule of OIHMIP were also studied. As characterized by atomic force microscope, the morphology of OIHMIP is sphere and the diameter of the spheres ranges in 150-200 nm. The experimental results show that OIHMIP has a high adsorption capacity and good selective recognition for 2,4-D, and reversible uptake and release of 2,4-D upon alternate irradiation at 365 and 440 nm, respectively.