Ultrapure Water Technology: Inert Framework of Ion Exchange Resin Structure

Understanding the structure of ion exchange resins is crucial for studying their performance and developing ion exchange resin technology. It allows us to effectively improve resin performance, synthesize ion exchange resins with specific properties, and provides important guidance for the correct selection of suitable ion exchange resins.

Ion exchange resin is a polymer electrolyte, a porous, sponge-like polymer compound with a three-dimensional spatial network structure. It generally consists of three parts: an inert backbone, fixed groups, and functional groups. Its inert backbone is composed of an irregular macromolecule (a carbon chain encircling a molecular weight), and is an intermediate product in the preparation of ion exchange resins. Introducing different functional groups into the inert backbone results in a resin with ion exchange properties. The degree of crosslinking, pore structure, and density of the inert backbone are important parameters affecting the performance of ion exchange resins.

Inert Backbone

Degree of Crosslinking A certain amount of crosslinking agent needs to be added during resin synthesis to give the ion exchange resin a specific structure and strength (microporous structure, porosity, and density). In the synthesis of styrene and acrylic resins, divinylbenzene (DVB) or glyceryl triacrylate is generally added as a crosslinking agent. Resins that do not use DVB as a crosslinking agent are called non-DVB resins, and itacone dielyl is generally used instead. The degree of crosslinking of an ion exchange resin network is expressed as the percentage of the crosslinking agent added during resin synthesis relative to the total mass of the monomer resin. That is: Degree of crosslinking = Mass of crosslinking agent in resin (g) / Mass of resin (g) x 100%.

The more crosslinking agent added, the greater the degree of crosslinking, the higher the strength of the resulting resin, and the lower its swelling in water. Simultaneously, the degree and range of crosslinking determine the pore structure of the resin. An appropriate degree of crosslinking is beneficial, but when the crosslinking is too high and the structure is too dense, large molecular ions have difficulty penetrating, and the penetration rate is also low.

(To be continued. This article is provided by Sichuan Youpu Ultrapure Technology and may not be reproduced without permission.)