Zirconium compounds exist in aqueous and solvent solution as polymeric species, and the properties exhibited by these polymeric species depends on chemical composition and mode of preparation. The polymeric species of zirconium can interact with functional groups on organic polymers. Zirconium reacts strongly with carboxyl groups (such as those of CMG , CarboxyMethylGuar) forming strong bonds. Hydrogen bonds are also formed with hydroxyl groups, which can range from quite weak to fairly strong interactions. Polymeric zirconium species may be cationic (zirconium oxychloride), anionic (ammonium zirconium carbonate, AZC), or neutral (zirconium acetate). Crosslinking Guar with Zirconium is one way reaction and is not reversible.
Soluble zirconium compounds (normally carboxylates) have a similar polymeric structure, containing bridging hydroxyl groups. The carboxylated species may behave as bidentate bridging agents. The carboxylates determine solvent solubility; different carboxylates exhibit solubilities in organic solvents. AZC may easily cross-link hydroxylic polymers or carboxylated polymers . The hydroxylic side groups of guar gum could react with AZC to form a guar gum gelation compound, and the carboxyl side groups of CMG are readily available for reacting with AZC to form CMG(CarboxyMethylGuar) crosslinks to produce gelled material.
