Imaging Radial Distribution Functions of Complex Particles by Relayed Dynamic Nuclear Polarization

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• The physical properties of multi-component materials are dictated by their internal microstructure.
• Characterizing nanoscale architectures is crucial for designing materials with specific properties.
• Existing methods like electron microscopy struggle with contrast for organic-only composites, common in pharmaceuticals and polymers.

Purpose of the Study:

• To develop a new imaging technique for visualizing the internal structure of multi-component materials.
• To overcome the contrast limitations of traditional methods for organic materials.
• To leverage nuclear magnetic resonance (NMR) spectroscopy's chemical shift capabilities for enhanced contrast.

Main Methods:

• Utilized dynamic nuclear polarization (DNP) to obtain hyperpolarized nuclear spins.
• Employed NMR measurements to track the relay of this nuclear hyperpolarization.
• Developed a method to reconstruct radial images of particle interiors from DNP-enhanced NMR signals.

Main Results:

• Successfully generated radial images of hybrid core-shell particles with nanometer resolution.
• Demonstrated the method's efficacy on polystyrene core/mesoporous silica shell particles.
• Showcased the ability to distinguish and image different components within the composite structure.

Conclusions:

• The DNP-enhanced NMR method provides high-resolution imaging of multi-component material microstructures.
• This technique offers a viable solution for contrast challenges in organic-rich composite materials.
• The developed imaging approach has significant potential for materials design and characterization.