*2.2.7. Microstructure*

AX1 and AX2 gels at 10% (w/v) were frozen in liquid nitrogen and lyophilized at −37°C/0.133 mbar overnight in a Freezone 6 freeze drier (Labconco, Kansas, MO). The microstructure of the freeze-dried gels was studied by scanning electron microscopy (SEM) (JEOL 5410LV, JEOL, Peabody, MA, USA) at low voltage (20 kV) and Secondary Electron Imaging (SEI) mode [19].
