Optical Force Probes for Spatially Resolved Imaging of Polymer Damage and Failure

Abstract

Polymer deformation spans 7–10 orders of magnitude in length scales, making its analysis a significant challenge. Optical force probes (OFPs), functional molecular motifs in polymer mechanochemistry, enable the study of mechanical properties by undergoing force-activated optical changes, such as absorption, fluorescence, or chemiluminescence. This review highlights OFPs integrated within polymer materials, focusing on their mechanical properties, optical methods for force elucidation, and the insights they provide. Special attention is given to high-resolution microscopy combined with OFPs, enabling qualitative and quantitative imaging of material damage and failure at unprecedented spatial resolution. While binary OFPs respond at critical strain thresholds, ideal for detecting permanent damage and stress hotspots, continuum OFPs track strain proportionally through reversible optical mechanisms, providing dynamic, real-time strain mapping. Together, these systems advance material diagnostics, offering complementary capabilities to study stress distribution, improve durability predictions, and understand polymer failure mechanisms.