Nanoparticles Using a Micromixer

We synthesized size-controlled zeolitic imidazolate framework (ZIF-8) nanoparticles using a T-type micromixer. The nanocrystallization of ZIF-8 proceeds by a rapid coordination reaction of Zn 2+ ions and 2-methylimidazole (2-MeIM) in a highly concentrated solution. Therefore, a rapid mixing of the raw materials is required to control the size and morphology of ZIF-8 nanoparticles. First, we prepared ZIF-8 nanoparticles at various flow rates of raw materials to investigate the mixing performance of a T-type micromixer. The size of the ZIF-8 nanoparticles decreased with an increase in flow rates at Reynolds number (Re) < 2000 (regarded as laminar flow). However, the size and shape of the resultant nanoparticles did not depend on the flow rates at Re> 2000 (transition state between laminar flow and turbulent flow), demonstrating the high mixing performance. Further, we systematically examined the effects of temperatures and [2-MeIM]/[Zn 2+ ratios on the resultant ZIF-8 nanoparticles to elucidate the formation mechanism and to optimize th