Abstract: A method for producing an expanded rigid foam with sealed pores includes at least the following steps: a) a mixture is prepared containing at least: an anionic polymer suited for ionotropic gelation; a foaming agent; a source of multivalent cations, said multivalent cations not being released in the mixture a); and a solvent; b) the mixture is stirred so as to obtain a foam; c) a compound capable of releasing protons in a sufficient amount to release said multivalent cations is added to the foam such that the anionic polymer gels ionotropically; d) the foam is dried. A foam is obtained in this manner and an object (for example a package, a heat-insulating or flame-retardant material) is made from this foam.

Abstract: A method for manufacturing a membrane, which includes at least the following steps of: preparing a mixture that contains at least an aqueous solution of a cationic polymer whose pH is between 5 and 8, the cationic polymer having positively-charged groups in this aqueous solution, and an aqueous solution of an anionic polymer, the anionic polymer having negatively-charged groups in this aqueous solution; stirring the mixture; leaving the mixture to mature to cause the ionic interaction between positively-charged groups of the cationic polymer and negatively-charged groups of the anionic polymer, until obtaining within the mixture a membrane in the form of a hydrogel; adding at least one crosslinking agent so as to crosslink the membrane; drying the crosslinked membrane obtained upon completion of the previous step. This membrane is used for the treatment of liquid or gaseous effluents, as well as an antimicrobial support or for heterogeneous catalysis.

Abstract: A method for producing an expanded rigid foam with sealed pores includes at least the following steps: a) a mixture is prepared containing at least: an anionic polymer suited for ionotropic gelation; a foaming agent; a source of multivalent cations, said multivalent cations not being released in the mixture a); and a solvent; b) the mixture is stirred so as to obtain a foam; c) a compound capable of releasing protons in a sufficient amount to release said multivalent cations is added to the foam such that the anionic polymer gels ionotropically; d) the foam is dried. A foam is obtained in this manner and an object (for example a package, a heat-insulating or flame-retardant material) is made from this foam.