Further rapidly reacting ion‐exchange resins

Abstract

To overcome the very slow reaction rates of weak electrolyte ion‐exchange resins in neutral salt solutions, the resins must be used as microparticles. Ways of handling microparticles are outlined. The present study is aimed at the preparation of large composite particles containing basic and acidic polymers in domains which are clearly segregated so that minimum interaction between the sites of opposite character occurs. Because the domain size is small, rapid reaction rates are achieved. Resins which show this effect have been prepared from basic and acidic monomers by using blocking procedures involving counterions, which significantly reduce the association of the basic and acidic sites. However, although very rapid reaction rates are obtained, the ion‐exchange capacities of the products remain inferior to those of composites made by binding the active microparticles together with an inert binder, showing that substantial self‐neutralization has still taken place. Similar results are obtained with basic and acidic monomers by using precipitation techniques, which are aimed at grafting one monomer onto a precipitated macroradical prepared from the other monomer.