Reversible electronic modulation of polydiacetylenes for sensing in dynamic conditions

Polydiacetylenes (PDAs) are renowned for their exceptional optical properties intricately linked to the polymer conformation, yet they exhibit poor conductivity in their undoped state. Despite this drawback, PDAs have garnered significant interest as sensing materials owing to their ability to undergo colorimetric shifts from blue to red in response to external stimuli. However, the irreversible nature of this transition has limited their utility in dynamic environments. In this study, we augment the sensing capabilities of PDA films beyond their irreversible optical response by inducing a reversible electronic response through conductivity modulation. We investigated polyamine-substituted PDAs with enriched hydrogen-bonding interaction sites for the concurrent changes in colorimetry and conductivity upon acetic acid (AA) vapor exposure. Coated on a flexible interdigitated electrode (IDE), we monitor the conductivity change throughout the blue-to-red phase transition. Remarkably, AA molecules act as dopants, significantly amplifying the system's conductivity. Although the PDA coating retains its red phase at postdopant removal, the electronic response reverts to its initial state, demonstrating reversibility. This reversible electronic response offers invaluable real-time insights into the specific triggers within dynamic environments, underscores the adaptability of responsive conjugated polymers, and highlights a promising avenue for their utilization in various sensing and monitoring applications.

Polyamine-terminated polydiacetylene film on an interdigitated electrode exhibits reversible electronic response at on/off acetic acid vapor exposure. image