An ion-immobilized elastomer comprising: an ion-immobilized metal oxide particle comprising: a cation of a reactive ionic liquid comprising an ion pair that consists of an anion and said cation; said metal oxide particle comprising a hydroxyl group, and an elastomer that comprises a functional group that is reactive with said hydroxyl group, said functional group being selected from a carboxyl group, an amino group or an epoxy group, the ion-immobilized metal oxide particle being immobilized to the elastomer via a bond between said hydroxyl group contained in the ion-immobilized metal oxide particle and the functional group contained in the elastomer, (a) the cation: being an imidazolium or quaternary ammonium cation; and comprising a reactive group that consists of an alkoxysilyl or phosphonate group, (b) the anion: being a sulfonate or nitrobenzoate anion, where, in the ion-immobilized metal oxide particle, the cation being immobilized to the metal oxide particle via an Si-O or P-O bond between the reactive group of the cation and the hydroxyl group of the metal oxide particle. an ion-immobilized metal oxide particle comprising: a cation of a reactive ionic liquid comprising an ion pair that consists of an anion and said cation; said metal oxide particle comprising a hydroxyl group, and an elastomer that comprises a functional group that is reactive with said hydroxyl group, said functional group being selected from a carboxyl group, an amino group or an epoxy group, the ion-immobilized metal oxide particle being immobilized to the elastomer via a bond between said hydroxyl group contained in the ion-immobilized metal oxide particle and the functional group contained in the elastomer, (a) the cation: being an imidazolium or quaternary ammonium cation; and comprising a reactive group that consists of an alkoxysilyl or phosphonate group, (b) the anion: being a sulfonate or nitrobenzoate anion, where, in the ion-immobilized metal oxide particle, the cation being immobilized to the metal oxide particle via an Si-O or P-O bond between the reactive group of the cation and the hydroxyl group of the metal oxide particle. a cation of a reactive ionic liquid comprising an ion pair that consists of an anion and said cation; said metal oxide particle comprising a hydroxyl group, and an elastomer that comprises a functional group that is reactive with said hydroxyl group, said functional group being selected from a carboxyl group, an amino group or an epoxy group, the ion-immobilized metal oxide particle being immobilized to the elastomer via a bond between said hydroxyl group contained in the ion-immobilized metal oxide particle and the functional group contained in the elastomer, (a) the cation: being an imidazolium or quaternary ammonium cation; and comprising a reactive group that consists of an alkoxysilyl or phosphonate group, (b) the anion: being a sulfonate or nitrobenzoate anion, (a) the cation: being an imidazolium or quaternary ammonium cation; and comprising a reactive group that consists of an alkoxysilyl or phosphonate group, being an imidazolium or quaternary ammonium cation; and comprising a reactive group that consists of an alkoxysilyl or phosphonate group, (b) the anion: being a sulfonate or nitrobenzoate anion, being a sulfonate or nitrobenzoate anion, where, in the ion-immobilized metal oxide particle, the cation being immobilized to the metal oxide particle via an Si-O or P-O bond between the reactive group of the cation and the hydroxyl group of the metal oxide particle.