Ultrafast Proton Transfer in Polymer Blends Triggered by Shock Waves

We describe ultrafast proton transfer in the ground electronic state triggered by the use of shock waves created by high-speed impacts. The emission of Nile Red (NR), a polarity sensing dye, was used to probe the effects of shock compression in a series of polymers, including polymer Bronsted bases blended with organic acid proton donors. NR undergoes a shock-induced red-shift due to an increase both in density and in polymer polarity. In blends with poly(4-vinylpyridine) (PVP) and phenol, NR showed an excess shock-induced red-shift with a distinct time dependence not present in controls that are incapable of proton transfer. The excess red-shift first appeared with 0.8 km·s–1 impacts. Occurring in ca. 10 ns, this NR red-shift was caused by the formation of an ion pair created by shock-triggered proton transfer from phenol to PVP.