Akademik Veri Yönetim Sistemi
ASME International Mechanical Engineering Congress and Exposition (IMECE), Louisiana, Amerika Birleşik Devletleri, 29 Ekim - 02 Kasım 2023
Solvothermal synthesis of advanced materials with complex metal-organic frameworks, superlattice crystalline structures, or intermediate phases requires precisely controlled thermodynamic and kinetic conditions. Droplet-based microfluidics provide a controlled platform for the investigation of chemical and physical kinetic processes confined in picoliter reactors for faster transfer of heat and mass and uniform distribution of temperature and concentration. We used a transparent thermo-fluidic device on an inverted microscope with a fast camera to observe the solidification kinetics in monodisperse microdroplets of a supersaturated solution in a continuous phase of silicon oil. The precursor solution involved a zirconium chloride salt, organic ligands, and a solvent. We optimized the two-phase flow conditions to control the reactor size. Nucleation experiments were conducted at 50, 80, and 100 degrees C. The residence time required to start nucleation was identified by a change in color and form in the droplets indicating a phase change. Higher temperatures resulted in shorter residence times due to faster nucleation kinetics. We used an Arrhenius relation to model droplet shrinkage due to dissolution of the solvent in oil and to calculate the concentration of the precursor solution at nucleation. Miniaturization of the reaction environment in microfluidic systems proved to be powerful for better control and observation of phase transitions in supersaturated solutions and in optimizing the precursor recipes towards desired products.