POS4-0588
Multimodal Mechanochromic Sensing of Stress and Cracks via Polydiacetylene–Upconversion Nanoparticle Composites
Topic
S4. Colloids, Interfaces, and Molecular Assemblies for Functional Soft Materials
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Jongkyu Kim (UNIST)
Co-Author(s)
Abstract
Polydiacetylene (PDA) is a conjugated polymer that undergoes a blue-to-red colorimetric transition in response to external stimuli and has been widely studied as a colorimetric sensing material, yet its use for visualizing the stress and cracks generated by mechanical stimuli remains limited. Here, we designed a mechanically responsive PDA structure and combined it with upconversion nanoparticles (UCNs) to develop a multimodal sensing platform that exploits both colorimetric and luminescent responses.
A PDA composite film was fabricated by introducing siloxane and aromatic functional groups into a poly(vinyl alcohol) (PVA) matrix. The siloxane network anchored at the PDA terminal generated the mechanochromic response to mechanical stimuli, while the aromatic groups tuned network density and modulus to improve film flexibility without compromising the mechanochromic behavior.
Under tensile loading, the film exhibited a distinct blue-to-red colorimetric transition. In the free-standing configuration, it reached a colorimetric response (CR) of 55.9% at 20% strain, demonstrating strong mechanochromic behavior. In the bottom-attached configuration, a localized transition emerged at strains as low as ~1.25%, confining the color change to specific stress-concentration regions. Together, these results demonstrate strain-dependent and spatially selective mechanochromic responses.
To enable dual-signal detection, UCNs were integrated with the PDA film to produce simultaneous colorimetric and luminescent responses under deformation. A high-modulus UCN layer detected 300 μm microcracks—difficult to resolve by the PDA colorimetric signal alone through luminescence ON/OFF switching, and tuning the UCN composition yielded a range of emission colors for customizable optical read-out.
This study presents a multimodal mechanochromic sensing platform for visualizing mechanical stress and cracks, with applications in structural health monitoring and wearable sensors.
A PDA composite film was fabricated by introducing siloxane and aromatic functional groups into a poly(vinyl alcohol) (PVA) matrix. The siloxane network anchored at the PDA terminal generated the mechanochromic response to mechanical stimuli, while the aromatic groups tuned network density and modulus to improve film flexibility without compromising the mechanochromic behavior.
Under tensile loading, the film exhibited a distinct blue-to-red colorimetric transition. In the free-standing configuration, it reached a colorimetric response (CR) of 55.9% at 20% strain, demonstrating strong mechanochromic behavior. In the bottom-attached configuration, a localized transition emerged at strains as low as ~1.25%, confining the color change to specific stress-concentration regions. Together, these results demonstrate strain-dependent and spatially selective mechanochromic responses.
To enable dual-signal detection, UCNs were integrated with the PDA film to produce simultaneous colorimetric and luminescent responses under deformation. A high-modulus UCN layer detected 300 μm microcracks—difficult to resolve by the PDA colorimetric signal alone through luminescence ON/OFF switching, and tuning the UCN composition yielded a range of emission colors for customizable optical read-out.
This study presents a multimodal mechanochromic sensing platform for visualizing mechanical stress and cracks, with applications in structural health monitoring and wearable sensors.
