Sputter coater machine

Freeze-dried hydrogels were investigated before and after water uptake analysis by E-SEM (XL30 FEG Philips) at accelerating voltage of 10 kV. The samples were cut into small squares (2 mm diameter x 1 mm height), fixed on the aluminium stub using carbon tape and gold-coated using a BIO-RAD Sputter Coater machine. For pore size evaluation E-SEM images were analysed using an image software (ImageJ). Three images for sample type were analysed measuring 50 pores for each one. The pore size was averaged to give a mean pore size assuming all pores were circular.

Freeze-dried hydrogels morphology was investigated by JEOL JSM-5600LV Scanning Electron Microscope. Samples were cut into small squares (2 ​mm diameter x 1 ​mm height), fixed on the aluminium stub using carbon tape and gold-coated using a BIO-RAD Sputter Coater machine. Thus, these were finally analysed at a 6 ​mm working distance, a 20 ​kV operation voltage used at different magnifications (35x and 100x). The pictures were analysed through ImageJ software, to evaluate the frequency of pores diameter distribution for each sample. Three images for sample type were analysed measuring 50 pores for each one. The pore size was averaged to give a mean pore size assuming all pores were circular.