Molecular View on Supramolecular Chain and Association Dynamics

Area of Science:

• Polymer Science
• Materials Science
• Soft Matter Physics

Background:

• Supramolecular polymers rely on reversible non-covalent interactions for their properties.
• Understanding the dynamics of these associations is crucial for material design.
• Previous models often assumed relaxation times were primarily affected by bond dynamics.

Purpose of the Study:

• To investigate the chain and association dynamics in supramolecular polymer melts.
• To elucidate the impact of hydrogen bond breaking on the dynamics.
• To provide molecular insight into the space and time evolution of these dynamics.

Main Methods:

• Neutron spin echo (NSE) spectroscopy was employed.
• A well-characterized ensemble of linearly associating telechelic poly(ethylene glycol) melts with triple H-bonding end groups was studied.

Main Results:

• Hydrogen bond breaking significantly impacts the mode spectrum of polymer associates.
• The study demonstrates that H-bond breaking affects mode contributions, contrary to previous assumptions about relaxation times.
• NSE spectra directly reveal H-bond lifetimes in the supramolecular melt.

Conclusions:

• The instantaneous average of the molecular weight distribution governs the system response for both microscopic and macroscopic dynamics.
• This finding holds true at least within the applicability of the Rouse model.
• The study provides a more accurate understanding of dynamics in supramolecular polymer melts.