Segmented Flow Synthesis And Crystallization Process Of Typical Nitrophenol Initiating Explosives

The segmented flow contains two immiscible phases:one reaction droplet phase and one continuous phase. In principle, the droplets of the reaction phase are dispersed in the continuous phase which preferentially wets or coats the surface of the micro channel. Compared to conventional techniques, micro segmented flow is marked by a series of unique features, such as fast mixing, effective heat exchange and short residence time distribution. In this paper, segmented flow synthesis and crystallization process of typical nitrophenols initiating explosives including LTNR, BaTNR and Pb·BaTNR have been investigated. The particular research content and conclusions are as follows:(1) Micro segmented flow synthesis system has been designed and prepared, which are composed of microfluidic driving module, micro chemical reaction module, droplet storage chip module and crystal image online acquisition module.(2) The best synthesis conditions of LTNR were obtained by orthogonal experimental design of segmented flow. The conditions are composed of lead nitrate solution (with pH value of 4.5 and molar concentration of 0.15M), magnesium styphnate solution (with pH value of 4.0 and molar concentration of O.15M), and reaction temperature of 70℃. The online research of LTNR crystallization process indicates that nucleation starts after 4min, and crystal growth is rapid between 4min to 9min, but significantly slow down between 9min to 54min and stop after 54 min.(3) The best synthesis conditions of LTNR were obtained by orthogonal experimental design of segmented flow. The conditions are composed of barium nitrate solution (with pH value of 5.5 and molar concentration of 0.20M), magnesium styphnate solution (with pH value of 4.5 and molar concentration of 0.15M), and reaction temperature of 65℃.(4) Through the reproducibility experiment, it was indicated that LTNR and BaTNR synthesized with segmented flow is superior to conventional technique in crystal morphology, uniformity, purity and so on.(5) Pb·BaTNR synthesized with segmented flow was confirmed with XRD, FTIR, CLSM and DSC characterization.The research results show that micro segmented flow synthesis system has preferable applications in synthesis of nitrophenol initiating explosives. However, further work is required. The design must be optimized and great attention must be paid to chemical reaction kinetics and crystal growth mechanism.