Preparation Of Nanocrystals By Precipitation Method In Microchannel Reactor

The rise of nanotechnology has aroused the attention of researchers to nanocrystals.Nanocrystals include nano-medicine crystals and nano-energetic materials and so on.Nanomedicine reduces the volume of the drug particle,increases the dissolution rate,and is more conducive to human absorption,improves the bioavailability of the drug,reduces the relative concentration in the body,avoids the toxic effect of a large number of drugs,and improves the drug targeting.Nano-energetic materials have properties such as energy and crystal form of energetic materials under conventional particle size,while optimizing melting point,decomposition temperature,energy release,reducing sensitivity,improving safety,and thermal stability.In this paper,the microchannel reactor is applied to the field of nanotechnology to verify the laws of nanotechnology,prepare nanoibuprofen,and prepare nano-Octogen（HMX）.This article is based on the precipitation method to prepare nanocrystals,which includes chemical precipitation method and solvent-non-solvent method.The above two methods are used to prepare nanoibuprofen with stable metal coordination bonds.The chemical precipitation method obtained by controlling the variables in the 0.1 mol/L ibuprofen alkaline aqueous solution and the same concentration of Zr Cl₄ aqueous solution,the two-phase flow rate ratio was 1-1,the total flow rate was 50 m L/min,the experimental temperature was 10℃,and ultrasonic force was applied.Under the field conditions,the particle size of the obtained ibuprofen with stable metal coordination bonds was uniformly distributed at about 40 nm,and the largest was only 110 nm,and the particle size distribution was the narrowest.The solvent-non-solvent method used controlled variables to obtain a solution between 0.1 mol/L ibuprofen ethanol solution and 0.01 mol/L Zr OCl₂·8H₂O aqueous solution,the two-phase flow rate ratio was 1-15,the solvent phase flow rate was 1 m L/min,the total flow rate was 16m L/min,under the condition of the experimental temperature of 40℃,the average particle size of the obtained ibuprofen with stable metal coordination bond was 100 nm,and there were also a few unstabilized ibuprofen particles.The solvent-non-solvent method was used to prepare HMX.When water was used as the non-solvent phase,the influence factors of the solvent-non-solvent method in the microchannel reactor on the crystal size in a variety of low-concentration solvent phases were explored.The following conclusions are drawn:the nano-scale process in the microchannel reactor is actually a competitive process of the dissolution and growth of the material molecules in the solvent after mixing.When the dissolution is dominant,the higher the corresponding temperature,the smaller the total flow rate,the smaller the flow rate ratio,the more the number of plates,the better the nanoization effect;the growth dominant is the opposite of the above conclusion.The best experimental conditions for nanometerization of HMX by solvent-non-solvent method:dissolve HMX into saturated DMF solution as the solvent phase.When the non-solvent phase was water,the flow rate ratio of the solvent phase to the non-solvent phase is 1-14,the total flow rate was 15 m L/min,and the system temperature was under the condition of 10℃,the average particle size of the prepared flake HMX particles reached 370nm;when the non-solvent phase was ethanol,the flow rate ratio of the solvent phase to the non-solvent phase is 1-10,a total flow rate of 10 m L/min,and a system temperature of 40℃,the average particle size of spheres in the preparation of spherical-flake mixed HMX particles reaches 40 nm,and the average particle size of flakes reaches 600 nm.In the process of nanometering,it was discovered that HMX changed fromβ-type toγ-type.It had been verified that it had nothing to do with system temperature,non-solvent type,flow rate,and flow rate ratio,only the solvent itself.