Preparation And Catalytic Property Of Molecularly Imprinted Polysiloxane Microspheres

Molecularly imprinted technology is one of the important methods to synthesize enzyme-like polymer catalyst. Molecularly imprinted polymers were usually prepared by bulk polymerization. Most of molecularly imprinted polymers were based on free radical polymerization using unsaturated monomer, such as polystyrene, polyacrylic acid and polyacrylamide. This method has some disadvantages such as difficulty to control the polymerization process, and few cross-linking species to be chosen.Molecularly imprinted polysiloxane microspheres were prepared by non-covalent molecularly imprinted technology and suspension polymerization using methyltriethoxysilane as a functional monomer and 4-nitrophenol as a template. The morphology of molecularly imprinted polysiloxane microspheres was characterized by transmission electron microscopy (TEM). The results show that molecularly imprinted polysiloxane microspheres have an average diameter of 900 nm.The adsorption and catalytic properties of molecularly imprinted polysiloxane microspheres were investigated by UV-Vis spectrophotometer. The results showed that molecularly imprinted polysiloxane microspheres can effectively adsorb 4-nitrophenol in solution. The non-imprinted polysiloxane microspheres could not catalyze the hydrolysis reaction of 4-nitrophenyl acetate. However, molecularly imprinted polysiloxane microspheres can increase hydrolysis rate of 4-nitrophenyl acetate in KH2PO4/K2HPO4 buffer (pH=7.6). In the beginning 100 minutes, the hydrolysis rate of 4-nitrophenyl acetate in the buffer with molecularly imprinted polysiloxane microspheres was 1.24 times than that of 4-nitrophenyl acetate only in buffer. The catalytic mechanism of molecularly imprinted polysiloxane microspheres was proposed.