Synthesis of a surface molecular imprinting polymer based on silica and its application in the identification of nitrocellulose

Abstract

A surface molecular imprinting polymer (MIP) based on silica (SiO2/MIP) with excellent selective identification properties towards nitrocellulose (NC) was synthesized with methylacrylic acid as a functional monomer and NC as a template molecule, through simple in situ polymerization. The functional groups of SiO2/MIP were studied through Fourier transform infrared spectroscopy. The morphology, crystalline state and thermostability of SiO2/MIP were investigated respectively by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. Binding capacity and selectivity studies of SiO2/MIP for NC and its analogues were carried out through ultraviolet-visible spectrophotometry. The thermal analysis and study of crystalline states confirmed the successful imprinting of NC in the polymer networks. The optimized conditions were found to be a polymerization temperature of 45 °C and a functional monomer to cross-linking ratio of 1:3. The adsorption capacity of SiO2/MIP was improved considerably compared with that of polymers prepared by traditional imprinting technology, with a maximum adsorption amount of 1.7 mg mg-1 in 2 mg ml-1 NC solution, compared with an adsorption capacity of about 0.5 mg mg-1 for a traditional MIP. According to the selectivity study, more NC was adsorbed by SiO2/MIP than its analogues; the best adsorption capacity of SiO2/MIP for NC was approaching 5 times that for carboxymethyl cellulose (CMC). The results show that it would be possible to apply SiO2/MIP for the detection of NC, to give improved sensitivity in security checking and improved contaminant adsorption.