Electrospun polymer jets are imaged for the first time at an ultra-high rate of 10,000 frames per second, investigating the process dynamics, and the instability propagation velocity and displacement in space. The polymer concentration, applied volta
ge bias and needle-collector distance are systematically varied, and their influence on the instability propagation velocity and on the jet angular fluctuations analyzed. This allows us to unveil the instability formation and cycling behavior, and its exponential growth at the onset, exhibiting radial growth rates of the order of 10^3 s^-1. Allowing the conformation and evolution of polymeric solutions to be studied in depth, high-speed imaging at sub-ms scale shows a significant potential for improving the fundamental knowledge of electrified jets, leading to obtain finely controllable bending and solution stretching in electrospinning, and consequently better designed nanofibers morphologies and structures.
