Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

TL;DR

This study demonstrates that macrocycle threading on carbon nanotubes significantly enhances their effectiveness as polymer fillers, leading to substantial improvements in mechanical properties of the resulting composites.

Contribution

It introduces mechanically interlocked derivatives of SWNTs (MINTs) as superior polymer fillers, showing enhanced mechanical performance over pristine nanotubes and supramolecular models.

Findings

Up to 200% increase in Young's modulus and tensile strength.

MINTs promote elongated polymer conformations at the interface.

Molecular dynamics confirm more efficient nanotube-polymer interactions.

Abstract

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.