Type V Reactive Separation

Ionic polymerizations commonly involve two types of propagating species— an ion pair (II-IV) and a free ion (V)—coexisting in equilibrium with each other. The relative concentrations of these two types of species, as also the identity of the ion pair (that is, whether of type II, ID, or IV), depend on the particular reaction conditions and especially the solvent or reaction medium, which has a large effect in ionic polymerizations. Loose ion pairs are more reactive than tight ion pairs, while free ions are significantly more reactive than ion pairs. In general, more polar media favor solvent-separated ion pairs or free solvated ions. In hydrocarbon media, jffee solvated ions do not exist, though other equilibria may occur between ion pairs and clusters of ions (Rudin, 1982). 

Sanchez J.M., Hidalgo M., Salvado V. S)mthesised phosphine sulphide-type macro-porous pol)nners for the preconcentration and separation of gold(III) and palladi-um(II) in a column system. Reactive and Functional Polymers 2001 49 215-224. 

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