2.1 Gel preparation
The chitosan is dissolved in an acetic acid solution (pH = 4). The prepared solution is injected
drop by drop using a syringe in a gelling solution (solution of sodium hydroxide 3M or sodium
dodecylsulphate solution 50mM). The obtained solution is maintained for 6 hours at room
temperature (25°C). Obtained hydrogel (in the form of balls) is filtered, then immersed in baths
containing ethanol/water solutions of which the proportions are: 1/9, 3/7, 5/5, 9/1, 1/0. One obtains
finally an alcogel, which thereafter undergoes an evaporative drying or a drying with supercritical
CO2.