Synthesis of Ion Exchange Resins:

It has been made clear earlier which we will mostly focus on synthesis and properties of organic resins. If we take synthesis, there are several types of resins and different chemical routes are followed to prepare them. Thus, it might be hard to cite here even the few significant ones. Therefore, to highlight the synthetic chemistry of ion exchange resins, some discussion will be taken up on common terms and which will be accompanied through a few examples of synthesis. One point which is extremely clear about synthesis of ion exchange resin is that it must yield a three dimensional cross-linked matrix of hydrocarbon chains carrying fixed ionic groups. This can be achieved in the subsequent ways:

i) Monomeric organic electrolytes could be polymerized in such a way in which a cross linked network is formed.

ii) The matrix could be built from non- ionic monomers and the fixed ionic groups are then introduced into the completed network.

iii) The fixed ionic groups are introduced while the polymerization is still in progress.

When synthesizing resinous exchanger, it should be kept in mind that it should be sufficiently cross-linked to have negligible solubility. The cross connected should be such in which it should be able to swell. Polymers that are too highly cross-linked cannot swell. The mobility of counter ions in such resins is so low that ion exchange is difficult to take place. The techniques of synthesis should be such that the degree of crosslinking can be controlled. Most of the ion exchange resins are made by either condensation polymerization or addition polymerization. Presently the addition polymerization processes have more or less replaced the condensation processes.