Real-Time Quantifying Microdroplet Synthesis of Metal-Organic Framework Colloids Using Gas-Phase Electrophoresis.

Area of Science:

• Materials Science
• Analytical Chemistry
• Chemical Engineering

Background:

• Metal-organic frameworks (MOFs) are versatile porous materials with applications in gas storage, separation, and catalysis.
• Microfluidic flow chemistry offers precise control over reaction conditions for synthesizing nanomaterials.
• Characterizing colloidal MOFs in real-time during synthesis is crucial for quality control and optimization.

Purpose of the Study:

• To develop and validate a hyphenated electrospray-differential mobility analysis (ES-DMA) technique for real-time characterization of colloidal MOFs.
• To investigate the influence of synthesis parameters on MOF colloid properties.
• To demonstrate the utility of ES-DMA for quality assurance in microfluidic MOF synthesis.

Main Methods:

• A hyphenated electrospray-differential mobility analysis (ES-DMA) system was integrated for real-time analysis.
• Zeolitic imidazolate framework-8 (ZIF-8) colloids were synthesized using microfluidic flow chemistry.
• Particle size and number concentration of MOF colloids were measured during the microdroplet synthesis process.

Main Results:

• The ES-DMA technique successfully characterized MOF colloids with high resolution and low measurement uncertainties (3 nm size, 4% concentration).
• The study identified key synthesis parameters, including temperature and precursor ratios, affecting MOF particle size.
• Accurate control over particle size, ranging from 100-200 nm, was achieved through parameter optimization.

Conclusions:

• The developed ES-DMA method provides a powerful tool for real-time quality assurance in microfluidic synthesis of colloidal MOFs.
• This approach enables efficient material optimization for tailored MOF properties.
• The findings pave the way for advanced control and scalable production of functional MOF nanomaterials.