Molecular Dynamics Insights into Behavior of Poly(ethylene succinate) Single Chain on Carbon Nanotube Surface

The
conformational properties of semiflexible polymer chains at
their interface with nanoscale organic fillers are classified as a
challenging subject due to the vast complexities involved, apart from
being the most critical phase of transcrystallization. An extensive
computational effort based on atomistic molecular dynamics has been
undertaken in this study in order to elucidate the behavior of a single
chain of a model aliphatic polyester, poly­(ethylene succinate), in
the vicinity of a single-walled carbon nanotube to gain new physical
insights into the conformational characteristics of this type of polymer.
The core finding is that the polymer chain transits from a coiled
to a folded shape in the process of adsorption on the nanotube surface
being a compromise of the dominant van der Waals interactions and
the chain configurational entropy. Varying temperature and chain length,
as well as the nanotube curvature, has been highlighted to be influential
on chain order parameter and spatial arrangement. Chain dynamics has
been found to obey the normal Einstein mode far from the nanotube
surface, while changes to Rouse type occur close to the interface.
The folded conformation of the polymer chain in the adsorbed state
explains structural ordering and growth normal to the nanotube surface.