Preparation Of Molecular Imprinting Polymer And Its Applicatrion In Detection Of Nitrocellulose

As a flammable explosive,nitrocellulose(NC)has been improperly used in terrorist attacks frequently.In order to prevent the occurrence of terrorist attacks and to control hazards,the traditional molecular imprinting polymer(TMIP)was synthesized with the NC as template and the surface molecular imprinting polymer based orn SiO2(SiO2/MIP)was prepared with SiO2 as nuclear material through molecularly imprinted technology.And through Fourier transform infrared(FT-IR)spectroscopy,scanning electron microscope(SEM),thermogravimetric analysis(TG)and X-ray diffraction(XRD)analysis,the functional groups,morphology,thermostability and crystalline state of TMIP and SiO5/M2P were investigated respectively.The adsorption capacity of TMIP and SiO2/MIP to NC was studied through ultraviolet-visible(Uv-vis)spectrophotometer.Polymerization temperature and ratio of functional monomer and crosslinking agent of prepared polymer were optimized.Compared with the structural analogues of NC including methyl cellulose,carboxyrnethyl cellulose and hydroxypropyl cellulose,the selectivity studies of the imprinted polymer on NC were carried out.With S1O2/MIP as sensitive membrane,the SiO2/MIP-based electrochemical sensor was Imade,through which the adsorption capacity of SiO2/MIP-based sensor to NC was studied through electrochemical method.The polymerization temperature,the ratio of imonomers and crosslinking agent,concentration of NC,incubation period and concentration of electrolyte potassium ferricyanide were optimized.This imprinting materials can be used in detection of nitrocellulose in security checking.From the results,the TMIP is amorphous and exhibits cross-linked networks in which many cavities are observed,while traditional non-imprinted polymer(TNIP)is observed to be many large agglomerates and amorphous.The degree of amorphous fonns of prepared polymer is increased when imprinted by NC molecule before the polymerization process.The weightloss process of TMIP is different from that of TNI-P,and the fonner is made up of tlree stages,while the latter includes two stages.The thermostability of TMIP and TNIP decreases with the increase of polymerization temperature and the quantity of crosslinking agent.According to the adsorption experiments,the adsorption capacity of TMIP to NC is much better than that of TNIP,which indicates the good specificity of TMIP to NC.The optimization conditions are found to be a polymerization temperature of 50°C and proportion of 1:3.The adsorption capacity of TMIP to NC is much higher than that to its structure analogues,which shows the good selectivity of TMIP to NC.From the SEM image of the synthesized SiO2/MIP,many cavities are observed in SiO2/MIP and the spherical silica is embedded in the polymer matrix,which indicates that the NC is successfully imprinted on the surface of SiO2.The prepared S1O2/MIP and surface non-imprinted polymer(SiO2/NIP)are amorphous,and the degree of crystallinity of SiO2/MIP is lower than that of SiO2/NTP.The weightloss processes of SiO2/MIP and SiO2/NIP are similar to that of TMIP and TNIP,respectively.Both polymerization temperature and concentration of crosslinking agent can reduce the thermal stability of SiO2/MJIP and SiO2/NIP.According to the adsorption experiment,SiO2/MIP has good specificity and selectivity to NC.The adsorption capacity of SiO2/MIP to NC is much higher than that of TMIP,which indicates that the surface imprinting can enhance the binding ability of imprinting polymer to NC.The optimization conditions of prepared SiO2/MIP electrochemical sensor to NC are found to be a polymerization temperature of 50?,proportion of 1:3,incubation period of lmin,and potassium ferricyanide concentation of 5.38 mmol/L.The adsorption capacity of SiO2/MIP and SiO2/MIP electrochemical sensors to NC increases with the rise of NC concentration and keeps stable finally.The detection limit of SiO2/MIP sensor to NC Is 3.4×10-3mg/mL,and the optimal NC concentration is 4mg/mL.The SiO2/MIP-based sensor has a large effective electrode area and excellent reproducibility.Compared with SiO2/NIP-based sensor,a higher adsorption capacity of SiO2/MIP-based sensor to NC is observed under different conditions,which indicates that the SiO2/MIP-based sensor has excellent specificity for NC.