Cryogels freezing temperature/rate

Fig. 4 Effect of the thawing rate on (a) the shear modulus and (b) the fusion temperature of PVA cryogels prepared by freezing of aqueous polymer solutions at —20 °C for 18 h. PVA concentrations were 120 (i), 100 (2), and 80 g/L (3). (Plotted based on data from [44])...

Fig. 22 Optical micrographs at two different magnifications of thin sections of foamed PVA cryogels prepared from the fluid foam produced by whipping of aqueous polymer solutions in the (a, b) absence and (c, d) presence of the surfactant CTAB at a concentration of 0.415 mM. Initial polymer concentration was 120 g/L. Cryotropic gelation conditions fieezing temperature —20 °C freezing duration 18 h, thawing rate 0.03 °C/min. (From [192] with permission from Springer)...

HEC cryogels of good quahty and high GF yield can be prepared by freezing the initial solution at a temperature between —15 and —30 °C at a cooling rate of 1 °C/min (Fig. 5). Note that the maximum value of GF yield is reached at —20 C. 

---