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Focus | New Breakthrough in Crystal Production Technology! BIT Scholars Published Research Results in Nature!

release date :2020-03-18 09:11:00  |   [ close window ]ViewCount:

NatureScience and technology
can make a prosperous nation and a strong country.
BITers advance wave upon wave and scale the new heights
on the way to revitalize China by applying scientific and technological advances.
In the special spring of 2020,
the pace of scientific research is stepped up.
Recently,
BIT scholars have made major scientific breakthroughs
in the field of crystal production technology,
and the scientific research results were published
in the international top journal Nature

  Recently, Prof. Sun Jianke, Teli Scholar, School of Chemistry and Chemical Engineering, BIT, published his research results of “shear promotes crystal growth” in the journal Nature (2020, 579, 73-79) under the title of Enhancing Crystal Growth Using Polyelectrolyte Solutions and Shear Flow. Prof. Sun is the first co-author of the paper, and BIT is the third co-operative unit. The study was conducted in collaboration with Prof. Bartosz Grzybowski of the Korean Basic Science Institute (KBSI).

  The preparation of high-quality single crystals with appropriate particle sizes is of vital importance in related industries such as Organic Synthesis and Pharmaceuticals. High-quality single crystal growth usually takes hours to days, and during this period, it is necessary to avoid external environmental disturbances. Based on the traditional crystallography theory, mechanical agitation and shear flow easily cause secondary nucleation, which is not conducive to crystal growth. However, Prof. Sun’s research overcomes the cognition of traditional crystal growth mechanism, and finds that in the environment where Poly (ionic liquid) (PIL, a type of polyelectrolyte material) exists, continuous stirring will make the crystal grow faster and larger.

  This method takes the small molecule of trimesic acid (TA) crystal as an example. In the presence of imidazole ionic liquid (3-cyanomethyl-1-vinyl imidazolium bis (trifluoromethanesulfonyl) imine polymer), after 10 minutes of stirring (400 rpm), the average size of crystal can reach 440 μm, which is 171 times larger than that of the system without stirring under the same conditions. This method is also much faster than the traditional room temperature volatilization method (which usually takes several days). More importantly, this method has a good universality, which can promote the growth of inorganic, organic, inorganic organic hybrid crystals and even some protein crystals. Moreover, compared with traditional methods, this method can effectively expand the specific surface area of porous materials, such as organic porous molecular cage, metal-organic framework and covalent organic framework. The BET specific surface area of the porous materials synthesized by this method has been improved by 24% to 51%.

Shear stress promotes the growth of TA crystals in the presence of polyionic liquids

  Further mechanism studies show that the acceleration of crystal growth in the shear field can be summarized as the synergy of the following two factors:
(1) Under shear stress, the polymer chain of the polyionic liquid will expand/stretch, competing with the solvent molecules, resulting in a decrease in the solubility of the solute and crystallization.
(2) The local shear rate is proportional to the particle size. The larger the crystal size is, the faster the crystal growth rate is.
For the second case, the study is further verified by (Computational Fluid Dynamics) CFD simulation. The results show that in shear flow, the local shear rate near the sharp edges of the particles increases with increasing particle size. Therefore, in the vicinity of larger particles, the disentanglement effect of polymer segments of polyionic liquids will be more significant, and the “competition” for solvents will be more effective, resulting in the preferential growth of large-scale crystals.

  This research overcomes the cognition of the traditional crystallization theory, the method of constant temperature crystallization with shear driven closed system is proposed, which provides a new idea for the simple and efficient synthesis of high-quality single crystals.

  Paper link: https://www.nature.com/articles/s41586-020-2042-1

Let us know some details about our outstanding BITer!

  Prof. Sun Jianke, Research Fellow of JSPS (Japan Society for the Promotion of Science), Humboldt Researcher, Teli Scholar, School of Chemistry and Chemical Engineering, BIT, mainly engages in the preparation and application of charge-modified porous materials, polyionic liquids and their composites. He has published more than 30 papers in Nature, Nature Commun, J. Am. Chem. Soc., Angew. Chem. Int. Ed., Chem. Soc. Rev. and Energy Environ. Sci., etc. as the first author / corresponding author. 4 of his papers were selected as ESI highly cited papers. The total number of the citation of his papers is over 2,000, and the h factor is 25.

Serving the major strategic needs of the country,
aiming at the forefront of world science and technology development,
determined to innovate and overcome difficulties,
BITers will strive for moving forward!

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