improved beads for use in the interfacial separation of anion and cation exchange beads are spherical , hydrolytically stable polymer beads having a controlled particle size , controlled density and a water wettability . the beads comprise a hydrophobic monomer , a hydrophilic monomer and a crosslinking monomer . the interface beads allow for the preparation of mixed - bed exchange resin compositions having improved life cycles and improved resin efficiencies .