Positively charged polyvinylidene fluoride membrane

A method of treating a composition, which method comprises filtering a composition through a filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer containing positively charged quaternary ammonium groups substantially only covalently bonded to said membrane in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer.

A filter cartridge comprising a filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer containing positively charged quaternary ammonium groups substantially only covalently bonded to said membrane in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer.

A method of treating a composition, which method comprises filtering a composition through a filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer containing positively charged quaternary ammonium groups substantially only covalently bonded to said membrane in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer, wherein said polymer is prepared from (a) diallyldimethylammonium chloride, (b) an acrylate selected from the group consisting of hydroxypropyl acrylate, hydroxyethyl acrylate, and diethylene glycol diacrylate, and (c) a methacrylate selected from the group consisting of hydroxyethyl methacrylate, polyethylene glycol dimethacrylate 600, hydroxypropyl methacrylate, and diethylene glycol dimethacrylate.

A filter cartridge comprising a filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer containing positively charged quaternary ammonium groups substantially only covalently bonded to said membrane in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer, wherein said polymer is prepared from (a) diallyldimethylammonium chloride, (b) an acrylate selected from the group consisting of hydroxypropyl acrylate, hydroxyethyl acrylate, and diethylene glycol diacrylate, and (c) a methacrylate selected from the group consisting of hydroxyethyl methacrylate, polyethylene glycol dimethacrylate 600, hydroxypropyl methacrylate, and diethylene glycol dimethacrylate.