The morphology of hydrogels was examined through cryogenic-scanning electron microscopy (cryo-SEM). A sample was placed between two Al holders (d=3mm) both containing a notch with a diameter of 2mm, inclosing the sample and creating a sandwich. Each sample was then flash-frozen in nitrogen slush at -210 °C, mounted on a (cryo-)transfer rod and transferred with a cryo-shuttle to the cryo-chamber by -140 °C under high vacuum (< 1•10 -3 mbar) (Leica ACE 400 Sputter Coater; Leica EM VCT100 cryo-shuttle). Here the samples were freeze fractured by knocking of the upper half of the sample, freeze-etched by -85°C for 15 minutes and subsequently sputter coated with a 3 nm platinum layer. The sample was finally moved to the SEM chamber (with the cryo-shuttle) where either fracture or top surfaces were observed at -140 °C, using acceleration voltages between 2-8 kV.