Surfaces and Interfaces of Liquid Metal Core-Shell Nanoparticles under the Microscope

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Eutectic gallium indium (EGaIn) is a promising liquid metal alloy for advanced core-shell nanoparticles (CSNs).
• Understanding ligand-nanoparticle surface chemistry is crucial for effective CSN stabilization.
• Ligand functionalization is key to controlling CSN properties.

Purpose of the Study:

• To investigate the role of aliphatic carboxylate ligand chain length in stabilizing EGaIn CSNs.
• To explore the surface chemistry at the ligand-EGaIn nanoparticle interface.
• To determine how ligand structure affects CSN size, stability, and mechanical properties.

Main Methods:

• Synthesis of EGaIn CSNs functionalized with aliphatic carboxylates (C2-C18).
• Characterization using Raman spectroscopy and diffuse reflectance Fourier transform spectroscopy (DRIFTS).
• Analysis of particle size and uniformity via atomic force microscopy (AFM).
• Measurement of CSN stiffness using AFM force-distance (F-D) measurements.

Main Results:

• DRIFTS confirmed the reaction between carboxylate ligands and the EGaIn nanoparticle oxide shell.
• Ligand chain length did not significantly alter CSN size but improved size uniformity with longer chains.
• AFM F-D measurements indicated conformational changes in alkyl chains upon compression, corroborating DRIFTS findings.

Conclusions:

• Aliphatic carboxylates effectively functionalize and stabilize EGaIn CSNs.
• Longer ligand chains enhance the uniformity of EGaIn CSN size.
• Ligand chain conformation and surface interactions are critical for understanding EGaIn CSN properties.