Monolithic, super heat-insulating, organic aerogel composition preparation method, said composition, and the use thereof

A gelled, dried and non-pyrolyzed composition forming an organic monolithic aerogel with a heat conductivity of less than or equal to 40 mW·m−1·K·1, the gelled, dried and non-pyrolyzed composition being based on a resin derived at least partly from polyhydroxybenzene(s) R and formaldehyde(s) F and being obtained by a process comprising:

• a) polymerization in an aqueous solvent W of said polyhydroxybenzene(s) R and formaldehyde(s) F in the presence of an acidic or basic catalyst and of at least one water-soluble cationic polyelectrolyte P dissolved in the solvent, to obtain a solution based on said resin,
• b) gelation of the solution obtained in a) to obtain a gel of said resin,
• c) drying of the gel obtained in b) to obtain a dried gel, and
• d) heat treatment under inert gas of the dried gel at temperatures of between 150° C. and 500° C. to obtain the gelled, dried and non-pyrolyzed composition forming the aerogel
• wherein the gelled, dried and non-pyrolyzed composition;
• comprises the at least one water-soluble cationic polyelectrolyte P which is used in the solution of step a) in a mass fraction of between 0.2% and 2%, and
• has said heat conductivity which increases by less than 10% and less than 20%, respectively, after 1 hour and 2 hours of exposure to a humid atmosphere regulated at 20° C. and 65% relative humidity, said heat conductivity being measured with a Neotim conductimeter via the hot wire technique according to standard ASTM D5930-97.