Using chemistry to monitor mechanical stress in polymers

Soft polymers are used in many structural materials, where they are frequently exposed to varying mechanical stress. Understanding how these polymers respond to and are damaged by that stress is crucial for engineering applications. Key tools to study that response are mechanophores: chemical compounds that exhibit a detectable response when exposed to a specific type of mechanical stimulus.

Sun et al. discussed how mechanophores could be used to provide a comprehensive picture of damage in polymers. Their approach focuses both on the chemical nature of mechanophores and the response they produce from damaged networks.

“Many existing studies only focus on either mechanophore chemistry or mechanical testing separately, without an integrated research perspective,” said author Rui Xiao. “Our group has conducted interdisciplinary work covering mechanophore design as well as chemo-mechanical damage modeling.”

Mechanophores are generally categorized into two broad groups: scission-type probes and ring-opening probes. Scission-type probes are further divided into mechanoluminescent and mechanofluorescent variants. Mechanoluminescent probes emit light when chemical bonds break within polymers, while mechanofluorescent probes generate fluorescence to visualize damage around cracks.

Ring-opening probes, in contrast, produce reversible optical signals that can identify permanent network damage under cyclic loading. Together, these varying types of mechanophores can provide a comprehensive understanding of the ways polymers behave and fail in response to stress.

This interdisciplinary approach, combining chemical signaling with mechanical analysis, can provide valuable tools to design and build stronger polymer-based materials in the future.

“I am most interested in building connections between molecular-level damage knowledge and macroscopic material performance,” said Xiao. “We want to use mechanochemistry to better understand fracture and fatigue behaviors of polymers and apply this fundamental knowledge to guide rational material design.”

Source: “Mechanochemistry: A new tool to detect damage in polymers,” by Peng Sun, Tianle Zhang, Yongzhe Jiang, and Rui Xiao, MechanoEngineering (2026). The article can be accessed at https://doi.org/10.1063/5.0351146 .