Understanding interactions between poly(styrene‐co‐sodium styrene sulfonate) and single‐walled carbon nanotubes

Abstract

Understanding formation mechanisms of hybrids of carbon nanotubes (CNTs) wrapped by polymers and their interactions is critical in modifying solubility of CNTs in aqueous solution and developing new nanotube‐based polymer materials. In the present work, we investigate the structural details of poly(styrene‐co‐sodium styrene sulfonate) (PSS) wrapping around the CNT and the interactions between the PSS chain and the CNT using molecular dynamics (MD) simulations. The fraction of sulfonated groups significantly influences the wrapping conformations of the PSS chain. Due to limited time scale in the MD simulations, two different initial conformations of the chains are introduced to explore the effect of the initial state on the wrapping behavior. When the chains initially wrap around the CNT in a perfect helix manner, more compact pseudo‐helical conformations are obtained. For initial straight line arrangement of the chain monomers, the chains adopt looser wrapping conformations. The free‐energy analysis and binding interaction of the PSS chain on the CNT surface take a glance on the relationship between the conformational transition of the chain and the energy evolution.

Polymer Wrapping State Changes at Defect Sites of Locally Functionalized Single-Walled Carbon Nanotubes

“…That is supported by the facts that D 2 O has much larger dielectric constant than polymers (D 2 O: 78; PVA: 7; , PVP: ∼4; PAA: 6; PSS (a partly sulfonated form): ∼20). Loose polymer wrapping can be attributed to electrostatic repulsion between the negatively charged PAA and PSS side chains of carboxylate and sulfonate groups, respectively. , Li et al reported that the PSS benzene­sulfonate groups were mostly arranged radiating outward from the SWCNT surface to interact with water molecules in their MD simulations, suggesting that a direct interaction between the hydrophilic polymer side chains and the SWCNT surface would be a minor contributor for the observed peak shifts in our experiments . In addition, they reported that increasing the number of the PSS units in the polystyrene copolymers induced looser wrapping of the SWCNT surfaces due to electrostatic repulsion of the side chains.…”

“…19 Although such interesting phenomena have been observed, a deeper understanding of polymer-wrapped SWCNTs at the molecular level is necessary to elucidate the mechanism leading to the interesting phenomena and to facilitate the design of custom functionalities. 20,21 As a characteristic of the individualized semiconducting SWCNTs, PL in the near-infrared (NIR) region (800−2500 nm) is observed. 8 Recently, locally functionalized SWCNTs (lf-SWCNTs), synthesized by slight amount of chemical functionalization of SWCNTs, have been reported to emit red-shifted and brighter defect PL (E 11 * PL) compared to native PL from pristine SWCNTs based on the lowest energy transition (E 11 transition).…”

“…32,61 Li et al reported that the PSS benzenesulfonate groups were mostly arranged radiating outward from the SWCNT surface to interact with water molecules in their MD simulations, suggesting that a direct interaction between the hydrophilic polymer side chains and the SWCNT surface would be a minor contributor for the observed peak shifts in our experiments. 20 In addition, they reported that increasing the number of the PSS units in the polystyrene copolymers induced looser wrapping of the SWCNT surfaces due to electrostatic repulsion of the side chains. Salem et al reported polymer wrapping tightness effects on PL by adding salts to aqueous solutions of DNA-wrapped SWCNTs to adjust the ionic strength of the solutions.…”

“…reported an optical biosensor application for SWCNTs wrapped with an amphiphilic polymer that created molecular recognition sites for specific biomolecules of interest . Although such interesting phenomena have been observed, a deeper understanding of polymer-wrapped SWCNTs at the molecular level is necessary to elucidate the mechanism leading to the interesting phenomena and to facilitate the design of custom functionalities. , …”

Strategy for Constructing Epoxy Composites with High Effective Thermal Conductive Capability Based on Three-Dimensional Cellulose and Multiwalled Carbon Nanotube Network

“…Nevertheless, addition of a large amount of thermal fillers is required to achieve a satisfied TC of composites, but the mechanical properties of thermosets will be deteriorated. Among them, CNTs were considered as promising and application-prospective thermal management fillers due to their superior TC, tremendous mechanical strength, and large specific surface area. − In general, a simple mechanical mixing between CNTs and polymeric materials was the most ordinary approach employed to manufacture thermal conductive polymer-based composites. Cui et al prepared EP/r-MWCNT composites by dispersing raw multiwalled carbon nanotubes (r-MWCNTs) in epoxy resin.…”