Single-Particle Tracking To Probe the Local Environment in Ice-Templated Crosslinked Colloidal Assemblies

Area of Science:

• Materials Science
• Polymer Science
• Colloid Science

Background:

• Hybrid assemblies of colloids in polymer networks exhibit diverse mechanical properties.
• Understanding microstructure-property relationships is crucial for designing advanced materials.
• Ice templating produces macroporous monolithic structures with potential applications.

Purpose of the Study:

• To investigate colloidal dynamics in elastic versus plastic hybrid assemblies.
• To correlate microstructural differences with macroscopic mechanical responses.
• To identify the role of polymer crosslink distribution in mechanical behavior.

Main Methods:

• Single-particle tracking using fluorescence microscopy.
• Wavelet transforms to correct for imaging artifacts like stage drift.
• Analysis of mean squared displacement and van Hove distributions.
• Particle tracking microrheology to determine solid modulus.

Main Results:

• Plastic assemblies exhibit significantly larger spatial heterogeneity in particle motion compared to elastic assemblies.
• Particle diffusivities are broadly distributed in plastic scaffolds, unlike the peaked distribution in elastic ones.
• Microrheology reveals a wider distribution of modulus values in plastic scaffolds, contrasting with bulk measurements.

Conclusions:

• Spatial heterogeneity in particle dynamics and crosslink distribution underlies the distinct elastic and plastic behaviors of these hybrid materials.
• Single-particle tracking, corrected for drift, is a sensitive tool for probing microstructure-property relationships in colloidal assemblies.
• The findings provide insights into the design of mechanically robust and tunable colloidal materials.