Radius and chirality dependent conformation of polymer molecule at nanotube interface

TL;DR

This study uses molecular dynamics simulations to explore how polymer molecules, specifically polyethylene, conform at carbon nanotube interfaces, revealing dependence on nanotube radius, chirality, and temperature, with implications for nanomaterial design.

Contribution

It provides new insights into the conformational behavior of polymers on CNTs, highlighting the influence of nanotube structure and temperature on polymer wrapping and alignment.

Findings

Polyethylene forms entropy-driven domains on CNT surfaces.

Wrapping angles depend on CNT radius and chirality.

A nematic transition occurs around 280 K, aligning molecules along the tube axis.

Abstract

Temperature dependent conformations of linear polymer molecules adsorbed at carbon nanotube (CNT) interfaces are investigated through molecule dynamics simulations. Model polyethylene (PE) molecules are shown to have selective conformations on CNT surface, controlled by atomic structures of CNT lattice and geometric coiling energy. PE molecules form entropy driven assembly domains, and their preferred wrapping angles around large radius CNT (40, 40) reflect the molecule configurations with energy minimums on a graphite plane. While PE molecules prefer wrapping on small radius armchair CNT (5, 5) predominantly at low temperatures, their configurations are shifted to larger wrapping angle ones on a similar radius zigzag CNT (10, 0). A nematic transformation around 280 K is identified through Landau-deGennes theory, with molecule aligning along tube axis in extended conformations