Organization of polymer chains onto long, single-wall carbon nano-tubes: Effect of tube diameter and cooling method

Abstract

We use molecular dynamics simulations to investigate the arrangement of polymer chains when absorbed onto a long, single-wall carbon nano-tube (SWCNT). We study the conformation and organization of the polymer chains on the SWCNT and their dependence on the tube's diameter and the rate of cooling. We use two types of cooling processes: direct quenching and gradual cooling. The radial density distribution function and bond orientational order parameter are used to characterize the polymer chain structure near the surface. In the direct cooling process, the beads of the polymer chain organize in lamella-like patterns on the surface of the SWCNT with the long axis of the lamella parallel to the axis of the SWCNT. In a stepwise, gradual cooling process, the polymer beads form a helical pattern on the surface of a relatively thick SWCNT, but form a lamella-like pattern on the surface of a very thin SWCNT. We develop a theoretical (free energy) model to explain this difference in pattern structures for the gradual cooling process and also provide a qualitative explanation for the pattern that forms from the direct cooling process.

Structure and dynamics of an active polymer adsorbed on the surface of a cylinder

“…Besides the active force, our model is different from these studies: we don't consider the torsion energy in our polymer model and our cylindrical surface is smooth without the chiral arrangement of beads. Thus, we observed a helix-like conformation, which is, strictly speaking, not the helical conformation found by Tallury 38 and Kumar et al 39 It is like a state between non-helical loop 7 and helical conformation.…”

“…They found that the flexible polymer tends to wrap around the SWCNT without any distinct conformation while a semi-flexible polymer wraps around the tube in a helical conformation. Kumar et al 39 studied the arrangement of polymer chains on a long SWCNT and they found a lamellar configuration on the SWCNT of the smallest radius due to the smaller torsion energy penalty. In an equilibrium state, the conformation of the polymer results from the competition between elastic energy and entropy.…”

Enrichment of large‐diameter semiconducting single‐walled carbon nanotubes by a mixed‐extractor strategy

“…In addition, to further confirm the flexibility of P8BT and PDFP molecular chains, Equation is used to define the radius of gyration, Rg …”

Semi-flexible polymer engendered aggregation/dispersion of fullerene (C60) nano-particles: An atomistic investigation

“…The Nose-Hoover thermostat [44,45] was implemented to control the desired temperature of the system along with the velocity-Verlet algorith m [46] with a time step of 1 fs. The simulation temperature was decreased from 800 K to 300 K in the steps of 50 K. Simulations were run for 1000 ps at each temperature step during cooling as reported in our previous studies [47,48]. The values of all parameters for polymer nano-particle system were based on the DREID-ING [49] force field.…”