Fluorogenic Conjugated Polymer Fibers from Amphiphilic Diacetylene Supramolecules

We have developed a simple strategy for the preparation of fluorogenic polydiacetylene fibers. The diacetylenic isophthalic acid PCDA-IPA was found to form microfibers when warm aqueous ethanolic solutions are cooled to room temperature. Irradiation of the self-assembled diacetylene wires with 254 nm UV light afforded blue-colored polydiacetylene wires, as evidenced by optical, fluorescence and scanning electron microscopic analyses. Relatively long polymer ribbons (ca. 100 μm) were obtained when 30–50% H2O-EtOH solvent systems are used while much shorter wires (< 10 μm) form in 60% H2O-EtOH. Thus, wire lengths can be varied by changing solvents. Importantly, the nonfluorescent polymerized ribbons were transformed to fluorescent PDAs upon heating. The observations made in this effort should be useful in the development of new and interesting PDA-based materials.