Anomalous self-diffusion and sticky Rouse dynamics in associative protein hydrogels

Area of Science:

• Polymer Science
• Soft Matter Physics
• Biomaterials

Background:

• Associating polymers form networks with tunable properties.
• Molecular and macroscopic dynamics are understood, but self-diffusion of network constituents is less clear.

Purpose of the Study:

• To investigate the self-diffusive dynamics of network-forming constituents in model associating protein hydrogels.
• To elucidate the relationship between molecular dynamics, network structure, and macroscopic properties.

Main Methods:

• Forced Rayleigh scattering to observe anomalous self-diffusion.
• Bulk rheology measurements to determine dissociation times.

Main Results:

• Anomalous self-diffusion was observed and quantitatively modeled using a two-state model.
• Diffusivity in the associated state was found to be critical for super diffusive behavior.
• Rheology revealed a hierarchy of relaxation processes, including sticky Rouse-like relaxation.

Conclusions:

• Experimental demonstration of a hierarchy of relaxation processes in associating polymer networks.
• Findings provide insights into the dynamics of sticky bonds, single molecules, and the overall network.
• Results are generalizable to other associative systems for understanding structure-property relationships.