SAXS measurements were performed at the high-throughput SAXS beamline B21, Diamond Light Source (Oxfordshire, UK). Frames of 500 ms were taken, and the 2D diffraction patterns were radially averaged and integrated to obtain 1D data.

The solvent background was subtracted and frames were averaged using the ScÅtter software. The number of frames averaged was varied to strike a balance between accessing greater time-resolution and achieving a better signal-to-noise ratio. For an X- ray irradiation time of ≤2 s, a single X-ray frame (500 ms) was used, whereas for >2 s, an average of 3 frames was used.

SAXS data were fitted using SASFit (version 0.94.11). The first 50 data points were removed due to aggregation effects in some samples. A linear, horizontal background was set to an appropriate value. The data were fitted to either: ellipsoidal cylindrical core- shell, ellipsoidal core-shell or spherical core- shell structures, with a Gaussian distribution around the (polar) radius to incorporate polydispersity into the model. Data were fitted to the radii (both polar and equatorial for ellipsoidal form factors), shell thickness, scattering length density and length (for cylindrical form factors). The structure factor was fitted using the Hayter–Penfold rescaled mean spherical approxima- tion (RMSA) model to determine the charge and volume fraction of the micelles. Full mathematical details of the models used are included in the associated publication (see Sharing and Access information).

UV–vis absorbance spectra were recorded using a Perkin Elmer Lambda 750 spectrometer with a slit width of 2 nm and a scan speed of 266.75 nm⋅min−1. Measurements were taken at 1 nm intervals from 700–200 nm, using quartz cuvettes with a 10 mm path length. The temperature was regulated to 25 °C using a Perkin Elmer Peltier temperature controller 201. Experimental data were background subtracted using water as a solvent reference.

Please see README_JONES_BEILSTEINJOC_2024.pdf for more details.