Disclosed are a copolymer, porous membranes made from the copolymer, and a method of treating fluids using the porous membranes to remove metal ions, for example, from fluids originating in the microelectronics industry, wherein the copolymer includes polymerized monomeric units I and II, wherein monomeric unit I is of the formula A-X—CH2—B, wherein A is Rf—(CH2)n, Rf is a perfluoro alkyl group of the formula CF3—(CF2)x—, wherein x is 3-12, n is 1-6, X is O or S, and B is vinylphenyl, the monomeric unit II is haloalkyl styrene, and optionally wherein the halo group of haloalkyl is replaced with an optional substituent, for example, ethylenediamine tetra acetic acid, iminodiacetic acid, or iminodisuccinic acid.