X-ray microtomography scan results. Composition A: sample prepared by mixing 40 g of 40 wt% CaCl2 solution (with 0.31 wt% tween 20 as surfactant) with 4 wt% HDK H18 fumed silica at 7000 RPM for 2 mins. Composition B: sample prepared by mixing 40 g of 40 wt% CaCl2 solution (with 2 wt% ethanol as surfactant) with 4 wt% Sipernat D10 precipitated silica at 7000 RPM for 30 s. Composition C: sample prepared by mixing 35 g of DI water (with 2.2 mM SDS as surfactant) with 2 wt% Aerosil R812S fumed silica at 7000 RPM for 30 s. Capsules from composition A were prepared by shaking a sample of the mixture (10-20 g) in a 500 ml plastic bottle. All samples were collected into a 3 mm plastic tube for imaging. Scans of larger volumes have lower resolution. For composition C, two scans (of different areas) with the same resolution are provided. Scan 2 was taken approx. 24 h after scan 1. The imaging was done using phoenix Nanotom S (Phoenix|x-ray Systems + Services GmbH, Waygate Technologies). The acceleration voltage was 60 kV, beam current was 200 µA and no additional beam filtering was used. For the scans with 5 µm voxel size, focus mode 0 of the device was used, and 600 projection images were recorded over a 360 degree turn with 3 x 500 ms exposure time at each projection. For the scans with 1.579 µm voxel size, focus mode 1 was used, and 1400 projection images were taken with 4 x 500 ms exposure time for each projection.

2024