Fig. 1. Conceptual scheme of the experiment.

Center: The train of x-ray pulses reaches the sample and heats it up in a controlled manner (red line in the right plot). If the silica nanoparticles are covered by PNIPAm, then the series of pulses will trigger the transition from the swollen hydrophilic to the collapsed hydrophobic state. In the top left plot, a typical DLS characterization of one of our core-shell systems is displayed, specifically a sample at high cross-linker concentration and thin shell thickness of ∼35 nm in the collapsed state.