Study On Preparation And Properties Of DMMP Molecularly Imprinted Film

Molecular imprinting is a method to prepare polymers with desired recognition site appeared in recent years. The molecular imprinted polymers (MIPs) are highly stable and able to bear high temperature, high pressure, acid or alkaline condition, and organic solution, alkaline condition, and organic solution. Due to their predetermination, specific recognition and practicability, MIPs have been largely put into use in catalysis, material chemistry, separation and biomimic sensor. Porphyrin complexes have become ideal material for the study of porphyrin sensors because of excellent properties of light sensitivity, chemical stability, easy modification, especially for that very a little of fluctuate involved could be monitored and be determinated either in the spectroscopy methods of UV-vis, IR, fluorescence, phosphorescence and Laman, or in elctroanalytical method conveniently. The porphyrin sensor film which preparaed by molecular imprinting method has been studied to detect the organophosphate pesticides mimics. This sensor film presents high sensitivity, quick response to dimethyl methyl phosphonate(DMMP). This research work will provide a novel way to quickly detect the pesticide residues.The coordination between DMMP and metalloporphyrin, the preparation and properties of DMMP molecularly imprinted film are mainly studied in this thesis. The research results were summarized as follows:The coordination between DMMP and metalloporphyrin was investigated by UV-Vis and fluorescence spectroscopies. The results showed that DMMP was employed as a guest to interaction with zinc tetraphenylporphyrin(ZnTPP) and cobalt tetraphenylporphyrin(CoTPP), respectively . And both of them could form 1:1 adducts. The Soret bands of ZnTPP were red-shifted and the absorbance of the Soret bands for CoTPP was reduced in the presence DMMP because of the flow of charge from the axial ligand to the porphyrin ring through the zinc and cobalt ion respectively. The equilibrium constants were determined at various temperatures to get the thermodynamic parameters to indicate the reactions were controlled by entropy.The molecularly imprinted film in the ZnTPP presence or not were prepared when DMMP was used as the template with the methacrylic acid as monomer, ethylene glycol dimethacrylate as crossing reagent and AIBN as initiator in imprinting reaction. In the preparation of film, the prepared conditions greatly affected the structure and property of resulting materials. When the temperature is at 15℃, the volume ratio of methacrylic acid, chloroform and ethylene glycol dimethacrylate is 1:1:2, the film is uniformity. In the preparation of porphyrin sensing film, the experimental result indicated that, the elution time is 150min, the dosage of molecular imprinting reaction liquid is 20μL, the film has good sensitive property and has a absorbency variety about 2% to 1×10-7 DMMP. The surface structure of the film has been characterized by contact angle measurements and SEM, and the film is uniformity with pore diameter of 30-100 nm.Porphyrin sensing film prepared by molecular imprinting has good sensitive property to DMMP. When responded to 1x10-7-1x10-9 DMMP, the film's absorbency changes evidently. And it has good reproducibility and selectivity to DMMP. Further more, the porphyrin sensor array showed remarkable results for detecting DMMP/N2 gas with 200ppm level.