Prof. Andrea Pucci and his team at the Department of Chemistry and Industrial Chemistry (DCCI) of the University of Pisa, Italy, have developed a new type of stretch-sensitive polymer film that changes fluorescence intensity when mechanically deformed. This is a double-layer mechanochromic system composed of an emissive bottom layer that emits fluorescence which changes under strain due to disruption of pyrene excimer aggregates, and an optical filter top layer that acts as a strain-dependent optical filter by changing light transmission during stretching.

This work demonstrates a scalable and relatively low-cost strategy for mechanochromic polymers by avoiding expensive mechanophore chemistries. Main applications to look out for include:

Structural health monitoring
Wearable strain sensors
Smart packaging
Responsive optical materials

A central experimental tool in the study was the Linkam Modular Force Stage (MFS), which enabled controlled mechanical testing during optical characterisation.

The Linkam MFS system was critical in this work because it allowed the researchers to directly correlate:

Mechanical deformation
Polymer morphology changes
Pyrene aggregate breakup
Fluorescence evolution

Without accurate strain control, the synergistic mechanochromic mechanism would have been difficult to validate quantitatively.

Find out more about the research here