The present invention relates to a method for preparing a metallized open-cell foam or fibrous substrate, wherein the method comprises: (A) providing an open-cell foam or fibrous substrate, wherein the open-cell foam or fibrous substrate contains a polymer comprising heteroatom-containing moieties within the bulk of the open-cell foam or fibrous substrate or as a coating on the open-cell foam or fibrous substrate, wherein the polymer comprising heteroatom-containing moieties is selected from polyvinylpyridine, polyvinylpyrrolidone, polyvinyl alcohol, polyallylamine, polyethylene oxide, polyethylene imine, polyethylene sulfide and copolymers or blends thereof; (B) contacting the open-cell foam or fibrous substrate with nanoparticles of a first metal to provide a nanoparticle coated open-cell foam or fibrous substrate; and (C) contacting the nanoparticle coated open-cell foam or fibrous substrate with a solution comprising a salt of a second metal and a reducing agent to provide the metallized open-cell foam or fibrous substrate having a layer of the second metal on the nanoparticle coated open-cell foam or fibrous substrate.

There is provided a carbon material dispersion which has excellent dispersibility and in which the dispersibility is retained stably over a long period of time even when the carbon material dispersion contains a carbon material at a high concentration. The carbon material dispersion is a carbon material dispersion containing a carbon material, water, and a polymeric dispersant, wherein the polymeric dispersant is a polymer including 5 to 40% by mass of a constituent unit (1) derived from a monomer 1, such as 2-vinylpyridine, 50 to 80% by mass of a constituent unit (2) derived from a monomer 2 represented by formula (1) (wherein R.sub.1 represents a hydrogen atom or the like, A represents O or NH, X represents an ethylene group or a propylene group, Y represents O, NHCOO, or NHCONH, each of R.sub.2 represents a hydrogen atom or the like, n represents 20 to 100, and R.sub.3 represents a hydrogen atom or the like), and 0.5 to 40% by mass of a constituent unit (3) derived from a monomer 3 copolymerizable with above-described monomers. ##STR00001##

Ion exchange membranes may include a polymeric microporous substrate, a cross-linked ion transferring polymeric layer on the substrate, and a hydrophobic coating on the cross-linked ion transferring polymer. The hydrophobic coating may comprise at least one of a weak base copolymer and an organosilicate compound.