Addition polymers:

Like cation exchangers, a commonly used anion exchange resin is prepared by copolymerization of styrene and divinylbenzene followed by chloromethylation (introduction -CH₂Cl grouping) say, within the para position and interaction along with a base such as trimethylamine. The polymers holding quaternary ammonium groups are strong bases and those with amino or substituted amino groups show weakly basic properties.