# Amplification of integrated microscopic motions of high-density [2]rotaxanes in mechanically interlocked networks

## TL;DR

This paper explores how microscopic molecular motions can be amplified to create materials with enhanced stretchability and toughness.

## Contribution

The study introduces a new class of mechanically interlocked networks with dense rotaxane backbones that exhibit amplified macroscopic mechanical properties.

## Key findings

- The integration of microscopic motions in [2]rotaxanes leads to enhanced stretchability and puncture resistance in the material.
- The dissociation and sliding motion of host−guest recognition provides an energy dissipation pathway, improving toughness and damping capacity.

## Abstract

Integrating individual microscopic motion to perform tasks in macroscopic sale is common in living organisms. However, developing artificial materials in which molecular-level motions could be amplified to behave macroscopically is still challenging. Herein, we present a class of mechanically interlocked networks (MINs) carrying densely rotaxanated backbones as a model system to understand macroscopic mechanical properties stemmed from the integration and amplification of intramolecular motion of the embedded [2]rotaxane motifs. On the one hand, the motion of mechanical bonds introduces the original dangling chains into the network, and the synergy of numerous such microscopic motions leads to an expansion of entire network, imparting good stretchability and puncture resistance to the MINs. On the other hand, the dissociation of host−guest recognition and subsequent sliding motion represent a peculiar energy dissipation pathway, whose integration and amplification result in the bulk materials with favorable toughness and damping capacity. Thereinto, we develop a continuous stress-relaxation method to elucidate the microscopic motion of [2]rotaxane units, which contributes to the understanding of the relationship between cumulative microscopic motions and amplified macroscopic mechanical performance.

Amplifying molecular motion to macroscopic material property is attractive but challenging. Here, the authors report mechanically interlocked networks with dense rotaxane backbones whose microscopic motion is integrated into decent mechanical properties of bulk materials.