Stabilization of Supramolecular Polymer Phase at High Pressures

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Supramolecular polymers self-assemble via non-covalent interactions like hydrogen bonding.
• EHUT monomers form viscoelastic networks and viscous phases based on tube and filament structures.
• Rheological properties are linked to structural transitions and thickness changes.

Purpose of the Study:

• Investigate the phase behavior of EHUT supramolecular polymers under high pressure (up to 1 kbar).
• Determine the influence of pressure on the viscoelastic network and viscous phases.
• Understand the molecular mechanisms behind pressure-induced structural transitions.

Main Methods:

• Dynamic Light Scattering (DLS) to probe structural dynamics.
• Passive Microrheology to measure viscoelastic properties.
• Molecular Dynamics (MD) simulations to analyze molecular packing and volume changes.

Main Results:

• A temperature-pressure phase diagram shows the viscoelastic network phase dominates at high pressures.
• Pressure induces a transition from filament structures (viscous) to tube structures (viscoelastic).
• Clapeyron equation analysis indicates a volume change of ~8 ų per EHUT molecule during the transition.

Conclusions:

• High pressure stabilizes the viscoelastic network phase of EHUT supramolecular polymers.
• Increased intermolecular contacts in tube structures, compared to filaments, explain the volume decrease.
• Pressure plays a crucial role in controlling self-assembly stability and material properties.