Loose Bulk Density and Length-to-Diameter Ratio of Flexible Needle-like Crystals Crown via Antisolvent Crystallization

Low
loose bulk density, a characteristic commonly observed
in large
accumulations of needle-like crystals, has caused numerous issues
in both production processes and daily life. Antisolvent crystallization,
known for its rapidity, localization, and minute crystals, presents
particular challenges in enhancing the loose bulk density of needle-like
crystals. In the study of β-nicotinamide mononucleotide, kinetic
analyses reveal that the induction period varies significantly with
antisolvent type, with the shortest induction period observed in methanol
reaching as low as 0.0067 s. Thermodynamic studies indicate that its
solubility in various antisolvent−water mixtures exhibits similar
trends with changes in solvent composition, although the equivalent
nucleation rates differ significantly. By simplifying the three-dimensional
molecular exchange to one-dimensional and reducing the interfacial
area between the solutions to slow the process, the resulting single
crystals can attain a maximum size over 1000 times larger than the
original microcrystals, making the flexible one-dimensional needle-like
crystals prone to fracturing and reducing the length-to-diameter ratio.
Similarly, when the actual three-dimensional molecular exchange within
droplets is slowed, the crystal can grow significantly in size while
being tightly assembled. Through crushing, the microscale flexible
needle-like crystals can be completely broken down, reducing their
length-to-diameter ratio, which in turn significantly increases the
loose bulk density.