TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of (I) comprises: solubilization of an optionally functionalized polymer in a solvent and separation of phase by contacting the obtained solution with at least a non-solvent, in which the solvent is miscible with non-solvent and has a certain affinity for this non-solvent.Preferred Components: The pores of (II) are at least partially obstructed by one or more compounds (mineral compounds (functionalized oxides of tin, titanium, silicon, boron or zirconium, phosphates and phosphonates of zirconium, tin or titanium and heteropolyacids) (preferably zirconium phosphate)) (10-50 (preferably 35) wt.%) having lower protonic conductivity than (II).Preferred Components: (III) is a functionalized polymer soluble in a solvent. The pores of (II) are obstructed by one or more organic polymers optionally functionalized by protogene groupings (carboxylic acid, phosphonic acid or sulfonic acid) (functionalized polyaromatic thermostable polymer (polysulfones, polyethersulfone, polyetherketones or polybenzimidazoles) (preferably sulfonated polyetherketone)). The pores of (II) lies between 0.1-5 microns. (I) further comprises one or more additives. The non-solvent is used in liquid and/or vapor form. The non-solvent is water and in which the solution obtained in the solubilization stage has hydrophilicity and a sufficient hygroscopicity, thus speed of inversion of the film is sufficiently high. The processing time of film obtained with water vapor is higher than 1 hour. The non-solvent in vapor and/or liquid form further comprises a solvent of polyetherketone and/or another non-solvent of polyetherketone.Preferred Process: The solution obtained in the solubilization stage is cast on a plane surface before contacting with the non-solvent. The polymer used in the solubilization stage is not functionalized and the solvent is appropriate to ensure the functionalisation. The method further comprises: dissolution of a polyetherketone in concentrated sulfuric acid which results in the sulfonation and concomitant dissolution of polyetherketone, casting of the obtained solution, inversion for contacting the obtained film with water vapor and delamination and inversion of the film by immersion of the latter in a water bath, where the concentration of the acid is approximately 96 wt.%, the time of contact between the acid and polyetherketone is 4-123 hours, the time required for water to be processed into vapor is lower than 5 minutes, the temperature of the bath is lower than 30degreesC, the time of contact in the water bath is approximately 1 hour and the membrane is washed in boiling water. The polymer used in the stage of solubilization was functionalized in a preliminary stage comprising dissolution of polyetherketone in concentrated sulfuric acid from which results sulfonation of polyetherketone, dissolution of sulfonated polyether in a solvent or a mixture of several solvents, casting of the obtained solution, contacting the obtained film with water vapor and/or contacting the film in a non-solvent bath. The method further comprises formation of organic polymers or particles of mineral compounds within the porous texture of (I) by precipitation, condensation or any other way. (I) undergoes a solvent exchange, an immersion in a source solution of zirconyl or zirconium ions (a solution of zirconyl propionate (0.25-0.5 mol/l) in ethanol or a zirconyl chloride solution in water, where the time of immersion of (I) in the solution of zirconyl propionate in ethanol is 30 minutes-2 hours) then a phosphoric acid treatment, from which results precipitation of zirconium phosphate within the porous texture of (I).