Structure sulfonated styrene/divinylbenzene

Figure 3.2 Example preparation method and chemical structure of a cation exchange membrane with sulfonated styrene-divinylbenzene copolymer.

Table 4-1. Structural and technical properties of surface-sulfonated styrene/divinylbenzene copolymers.

The ion exchange resins can be obtained either from the polymerization of substituted styrene or by the chemical modification of the polymer. For example, styrene/divinylbenzene (SDVB) polymer can be modified by chloromethylation (using HCl and formaldehyde in the presence of ZnCb) followed by reaction with a tertiary amine. This derivatization leads to a strong anion exchange material. Sulfonation of SDVB leads to a strong cation exchanger. The idealized structure of SDVB and of the anion and cation exchangers obtained from this material are shown below ... 

The ion-exchange resin is composed of a polymeric skeletal structure (e.g., copolymer of styrene and divinylbenzene), onto which ionic groups (e.g., —S03 ) are attached. The charges of the ionic groups are neutralized by counter ions, which can move freely within the polymer skeleton (e.g., H ). Figure 2.38 shows schematically the structure of an ion-exchange resin. In applications such as acid catalysts, they are typically used as sulfonated copolymer of styrene and divinylbenzene. The maximum temperature of operation is 120-150 °C, and pore volume and pore size distribution depend on the polarity of the reaction mixture. 

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