Study On Trace Detection Technology For High Energy Density Explosive CL-20

The third generation of high energy density explosives represented by CL-20 has been more and more widely used in recent years,while the trace rapid detection technology for them is still lacking in research.Molecular imprinting technology has attracted attention in the field of explosives detection with its specific,efficient and convenient characteristics,and this technology can achieve rapid and trace detection of explosives.In this paper,CL-20,a monomeric explosive,was used as a template molecule,and the functional monomers for the preparation of CL-20 molecularly imprinted polymers（MIPs）were firstly selected by theoretical analysis and calculation of the pre-polymerization system,and then the MIPs of CL-20 were prepared by emulsion polymerization and surface molecular imprinting techniques and made into electrochemical sensors,as follows:（1）For the CL-20 molecularly imprinted prepolymerization system,the geometric configuration of template molecule CL-20,functional monomers AM,MAA and AA was optimized at the level of B3LYP-D3/6-311G（d,p）group by Gaussian software based on density pan theory,and the binding energy of the possible formation of the complex system was calculated based on the results of NBO analysis,which showed that.The binding energy of CL-20-AM was the smallest,indicating that the composite system formed by CL-20 and AM was the most stable.The UV spectra and differential UV spectra of solutions with different molar ratios of CL-20 and three functional monomers were also used for analysis and calculation,and the experimental results further confirmed that the interaction between CL-20 and AM was the strongest,and its optimal ratio was 1:4.（2）MIPs of CL-20 were prepared by emulsion polymerization based on the results of the prepolymerization system study,and the successful preparation of MIPs was verified using electron microscopy,infrared and thermogravimetry.The adsorption experiments showed that:the adsorption process of MIPs was more consistent with the Freundlich adsorption model and pseudo-secondary kinetic equation for multilayer-specific chemisorption,with TNT and RDX as competing molecules for CL-20,the MIPs always showed better adsorption performance for CL-20 in different concentrations.After 6 adsorption-desorption experiments,the adsorption capacity of MIPs on CL-20 was reduced by 11.40%,which also has good reusability performance.（3）SiO₂@MIPs were prepared by surface molecular imprinting technique using amination-modified SiO₂ as the core material,CL-20 as the template molecule and AM as the functional monomer.Electron microscopy,infrared and thermogravimetry showed that the SiO₂ surface was successfully covered with an imprinted polymer film.The adsorption experiments showed that:the adsorption process of MIPs was more consistent with Freundlich adsorption model and pseudo-secondary kinetic equation,and it was multi-molecular layer-specific chemisorption.With TNT and RDX as competing molecules of CL-20,MIPs always showed better adsorption performance on CL-20,after six adsorption-desorption experiments,the adsorption capacity of MIPs on CL-20 decreased 11.40%,again with good reusability performance.（4）The MIPs prepared by emulsion polymerization method were used to prepare electrochemical sensors by surface coating method.The electrochemical detection performance of the sensor was investigated by cyclic voltammetry and differential voltammetric pulse method,and the experimental results showed that:the binding of CL-20by the MIPs sensor showed a parabolic distribution with the increase of potassium ferricyanide concentration,in different concentrations of potassium ferricyanide solution,the MIPs sensor always showed better adsorption capacity for CL-20 compared with the competing molecules TNT and RDX,the MIPs The apparent surface area of the MIPs sensor was much larger than that of the NIPs sensor（10.10 cm²>5.39 cm²）,the response of the DPV of the MIPs sensor was measured for 18 consecutive times with a relative standard deviation of 1.78%,which showed good reproducibility.