Sulfonated poly(arylene ether) membranes with high monovalent salt rejection even in the presence of mixed salt feeds that contain multivalent salts

A copolymer comprising the structure:

• where each L1 is independently
• wherein each L2 is
• wherein each L3 is independently a single bond,
• wherein at least one or both or all of Y1 is SO3Z, wherein Z is a counterion, and wherein each R is independently H, F, or CH3.

A method comprising:

• reacting HO-L2-OH with
• with or without an aminophenol, to generate a copolymer, wherein each L1 is independently
• wherein L2 is
• wherein L3 is a single bond,
• wherein each R is independently H, F, or CH3, and wherein X is a halogen.

A method comprising:

• (i) a method comprising:
• reacting
• one or more HO-L2-OH and
• with or without an aminophenol, to generate a copolymer with phenol or aminophenol endgroups, wherein each L1 is independently
• wherein L2 is independently
• wherein L3 is a single bond,
• wherein X is a halogen;
• and
• sulfonating the copolymer to generate a single SO3Z substituent on one or every aromatic ring of L2, wherein Z is a counterion;
• and
• conducting an end-functionalization reaction with
• acryloyl halide, methacryloyl halide, isocyanatoethyl acrylate, or isocyanatoethyl methacrylate to generate a post-sulfonated, end-functionalized copolymer or alternatively,
• (i) a method comprising:
• reacting
• one or more HO-L2-OH and
• with or without an aminophenol, to generate a copolymer with phenol or aminophenol endgroups, wherein each L1 is independently
• wherein L2 is independently
• wherein L3 is a single bond,
• wherein X is a halogen;
• and
• conducting an end-functionalization reaction with
• acryloyl halide, methacryloyl halide, isocyanatoethyl acrylate, or isocyanatoethyl methacrylate to generate a post-sulfonated, end-functionalized copolymer;
• initiating a crosslinking reaction by subjecting the end-functionalized copolymer to a crosslinking agent including one or more of heat, light, a free radical initiator, or an epoxy reagent, wherein the crosslinking reaction includes:
• crosslinking a blend of different molecular weights of the end-functionalized copolymer;
• or crosslinking a single molecular weight or blends of different molecular weights of the end-functionalized copolymer and one or more polymerizable reagents;
• and
• sulfonating the crosslinked copolymer to generate a single SO3Z substituent on some, one, or every aromatic ring of L2, wherein Z is a counterion.

A water desalination membrane exhibiting a rejection of aqueous monovalent ions of over 95% in the presence of polyvalent cations, the membrane comprising:

• a copolymer comprising the structure:
• where each L1 is independently
• wherein each L2 is
• wherein each L3 is independently a single bond,
• wherein at least one or both or all of Y1 is SO3Z, wherein Z is a counterion, and wherein each R is independently H, F, or CH3, wherein the membrane exhibits a rejection of aqueous monovalent ions of over 95% in the presence of polyvalent cations.