Autonomous Nanoparticle Synthesis Guided by In Situ Multiscale Structural Characterization

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Autonomous synthesis platforms offer rapid exploration of chemical parameter spaces.
• Integrating in situ structural characterization with closed-loop synthesis optimization is a significant challenge.

Purpose of the Study:

• To develop and demonstrate a closed-loop autonomous platform for synthesizing gold nanoparticles with targeted characteristics.
• To achieve precise control over nanoparticle size and polydispersity using in situ structural characterization.

Main Methods:

• Coupling a droplet-flow microreactor with in situ X-ray scattering (SAXS/WAXS) and Gaussian process optimization.
• Exploring a vast parameter space (∼19,000 recipes) through automated experimentation.
• Utilizing quantitative SAXS/WAXS and electron microscopy for structural analysis.

Main Results:

• Achieved precise control over gold nanoparticle size (4-60 nm) and low polydispersity (σ < 0.11).
• Discovered a universal relationship between crystallite size and particle size (dc = 0.18d + β), with synthesis chemistry controlling the intercept.
• Demonstrated independent tuning of crystallite domain size at fixed particle diameter.

Conclusions:

• The developed closed-loop platform provides a robust framework for mapping and controlling multiscale nanoparticle structure.
• This approach enables independent tuning of crystallite and particle size, expanding synthesis boundaries.
• The platform is applicable to a broad range of nanoparticle synthesis processes.