A process for functionalising inorganic particles by polymers comprising at least two different types of repeating units, called a first repeating unit and a second repeating unit, each carrying a different proton exchange group, said process comprising the following steps: a) a step of covalently grafting inorganic particles by an organic compound, by contacting said particles with a coupling agent comprising at least one group able to be covalently bonded to the particles, whereby this results in inorganic particles covalently bonded to an organic compound, which is a residue of said coupling agent, said residue further comprising a group able to covalently react with a functional group of the polymer from step d); b) a step of anionically polymerising at least two types of monomers, namely a first monomer and a second monomer different from each other, each carrying at least one precursor group for a different proton exchange group, whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including an anionic end; c) a step of termination reaction of the anionic polymerisation of step b) by contacting the polymer from this step with a termination agent including a group (called a group X) able to react with the anionic end of said polymer to form a covalent bond, whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including, at one end thereof, a residue of said termination agent; d) a step of functionalising the polymer obtained at the end of step c) by contacting the said polymer from step c) with a functionalising agent including a group (called group Z) able to react with a group (called group W) of said residue of termination agent to form a functional group able to covalently react with the particles obtained in step a), whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including, at one end thereof, said functional group covalently bonded to the residue of said termination agent; e) a step of contacting the particles obtained in step a) with the polymers obtained in step d) generating a covalent reaction between the functional group and the group of the residue of coupling agent defined in step a), whereby this results in inorganic particles covalently functionalised by polymers comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group; f) a step of transforming the precursor group(s) into proton exchange groups. a) a step of covalently grafting inorganic particles by an organic compound, by contacting said particles with a coupling agent comprising at least one group able to be covalently bonded to the particles, whereby this results in inorganic particles covalently bonded to an organic compound, which is a residue of said coupling agent, said residue further comprising a group able to covalently react with a functional group of the polymer from step d); b) a step of anionically polymerising at least two types of monomers, namely a first monomer and a second monomer different from each other, each carrying at least one precursor group for a different proton exchange group, whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including an anionic end; c) a step of termination reaction of the anionic polymerisation of step b) by contacting the polymer from this step with a termination agent including a group (called a group X) able to react with the anionic end of said polymer to form a covalent bond, whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including, at one end thereof, a residue of said termination agent; d) a step of functionalising the polymer obtained at the end of step c) by contacting the said polymer from step c) with a functionalising agent including a group (called group Z) able to react with a group (called group W) of said residue of termination agent to form a functional group able to covalently react with the particles obtained in step a), whereby this results in a polymer comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group and including, at one end thereof, said functional group covalently bonded to the residue of said termination agent; e) a step of contacting the particles obtained in step a) with the polymers obtained in step d) generating a covalent reaction between the functional group and the group of the residue of coupling agent defined in step a), whereby this results in inorganic particles covalently functionalised by polymers comprising at least two different types of repeating units each carrying a precursor group for a different proton exchange group; f) a step of transforming the precursor group(s) into proton exchange groups.