Polymer dynamics under cylindrical confinement featuring a locally repulsive surface: A quasielastic neutron
M Krutyeva1, S Pasini1, M Monkenbusch1
1Jülich Centre for Neutron Science (JCNS) and Institute for Complex Systems (ICS), Forschungszentrum Jülich GmbH, Jülich, Germany.
The Journal of Chemical Physics
|June 3, 2017
Summary
Polymer dynamics in nanopores with repulsive walls remain unchanged compared to the bulk. Repulsive confinement did not accelerate segmental motion or affect entanglement dynamics, contrary to some simulation predictions.
Area of Science:
- Polymer Physics
- Materials Science
- Nanotechnology
Background:
- Understanding polymer dynamics under confinement is crucial for materials design.
- Simulations predict altered dynamics near repulsive surfaces, but experimental validation is needed.
Purpose of the Study:
- To investigate the effect of cylindrical confinement with locally repulsive walls on polymer melt dynamics.
- To compare experimental results with simulation predictions regarding segmental and entanglement dynamics.
Main Methods:
- Quasielastic neutron scattering (QENS) and neutron spin-echo (NSE) experiments.
- Utilized hydrophilic anodic alumina nanopores (20 nm diameter) for confinement.
- Studied polyethylene-alt-propylene polymer melt.
Main Results:
- Segmental dynamics in nanopores were identical to bulk polymer melt mobility.
- No acceleration of surface-near segmental motion was observed.
- Rouse relaxation and entanglement dynamics were unaffected by confinement.
Conclusions:
- Locally repulsive confinement does not alter polymer dynamics at the segmental or entanglement level.
- Experimental findings contrast with some simulation predictions for polymer melts under confinement.
- Moderate confinement with repulsive walls maintains bulk-like polymer dynamics.
