Divinylbenzene-cross-linked polystyrene with metal complexes

Polystyrene and its divinylbenzene cross-linked copolymer have been most widely exploited as the polymer support for anchoring metal complexes. A large variety of ligands containing N, P or S have been anchored on the polystyrene-divinylbenzene matrix either by the bromination-lithiation pathway or by direct interaction of the ligand with C1-, Br- or CN-methylated polystyrene-divinyl-benzene network [14] (Fig. 7). 

Almost all industrial catalysts are heterogeneous, with the reaction taking place on a solid surface. The polymeric catalysts are formed by chemically bonding a transition metal complex to an insoluble polymer they are then useful as heterogeneous catalysts. Cross-linked polystyrene-divinylbenzene gel, phosphonated polystyrene-divinylbenzene, ion-exchange resin, and silica are well-known insoluble polymers that have been used. Examples of polymer reactions are as follows [Eqs. (16-23)] ... 

Along both routes linear or crosslinked materials can be used or obtained. Type I compounds with a linear backbone are soluble and can be coated to thin film devices. Crosslinked materials possess in dependence on the amount of crosslinking and procedure of copolymerization pores of different type and size with more or less uniform cross-linked density [79]. One example is amorphous polystyrene crosslinked with divinylbenzene. Non-porous examples are partially crystalline polymers like polyethylene and some inorganic carriers like silica gel. Ligand/metal ion/complex/chelate groups can be distributed on the whole polymer volume or localized only on the carrier surface and connection to the carrier is possible via a direct bond or spacer. All possibilities result in different relativities (properties) of the materials [80,81]. 

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