Preparation of resorcinol-formaldehyde carbon cryogel microhoneycombs

The preparation of resorcinol-formaldehyde (RF) hydrogels by the sol-gel polycondensation of resorcinol (R) with formaldehyde (F) using sodium carbonate (C) as a basic catalyst and distilled water (W) was discussed. It was found that the ratios of resorcinol to formaldehyde (mol/mol; R/F), resorcinol to water (g/cm³; R/W) and resorcinol to catalyst (mol/mol; R/C) were 0.5, 0.2 and 100 respectively. The resulting hydrogels were washed five times with distilled water and placed into polypropylene tubes, which were filled with distilled water. These tubes were frozen at a constant rate of 20 cm/h, by dipping the tubes perpendicularly into a cold bath.