An ion exchange chromatographic packing material comprising: a) support resin particles; and b) a copolymer grafted to the support resin particles, the copolymer comprising: i) an ion exchange group configured to have a polarity that does not change when switching from a first pH to a second pH, in which the first pH and the second pH are different, where the ion exchange group includes an ion exchange monomer that has been polymerized, ii) an ionic crosslinking group configured to ionically bind to the ion exchange group, where the ionic crosslinking group includes an ionic crosslinking monomer that has been polymerized, iii) an adjustable ionization state group having at least a first net charge at the first pH and a second net charge at the second pH, in which the first net charge and the second net charge are different, where the adjustable ionization state group includes an adjustable ionization state monomer that has been polymerized, where the ion exchange group, the ionic crosslinking group, and the adjustable ionization state group are different, and where an overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. a) support resin particles; and b) a copolymer grafted to the support resin particles, the copolymer comprising: i) an ion exchange group configured to have a polarity that does not change when switching from a first pH to a second pH, in which the first pH and the second pH are different, where the ion exchange group includes an ion exchange monomer that has been polymerized, ii) an ionic crosslinking group configured to ionically bind to the ion exchange group, where the ionic crosslinking group includes an ionic crosslinking monomer that has been polymerized, iii) an adjustable ionization state group having at least a first net charge at the first pH and a second net charge at the second pH, in which the first net charge and the second net charge are different, where the adjustable ionization state group includes an adjustable ionization state monomer that has been polymerized, where the ion exchange group, the ionic crosslinking group, and the adjustable ionization state group are different, and where an overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. i) an ion exchange group configured to have a polarity that does not change when switching from a first pH to a second pH, in which the first pH and the second pH are different, where the ion exchange group includes an ion exchange monomer that has been polymerized, ii) an ionic crosslinking group configured to ionically bind to the ion exchange group, where the ionic crosslinking group includes an ionic crosslinking monomer that has been polymerized, iii) an adjustable ionization state group having at least a first net charge at the first pH and a second net charge at the second pH, in which the first net charge and the second net charge are different, where the adjustable ionization state group includes an adjustable ionization state monomer that has been polymerized, where the ion exchange group, the ionic crosslinking group, and the adjustable ionization state group are different, and where an overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. where the ion exchange group, the ionic crosslinking group, and the adjustable ionization state group are different, and where an overall first net charge of the chromatographic packing material at the first pH is opposite in polarity to the overall second net charge of the chromatographic packing material. <EOS>