Immobilized phases free radical crosslinke

An alternative approach to stationary phase immobilization, and the most popular method in contemporary practice, is the free radical crosslinking of the polymer chains, using peroxides [201,202,245-248], azo-oospounds [202,249-251], ozone [252], or gamma radiation [253-255] as free radical generators. In this case, crosslinking occurs through the formation of (Si-C-C-Sl) bonds as shown below ... 

Polymer encapsulated sorbents have been prepared by peroxide-induced or ozone-induced free radical crosslinking of coated porous silica or diatomaceous supports at elevated temperatures [175]. By reloading and performing sequential crosslinking reactions up to 20% (w/w) of liquid phase can be immobilized over the support surface. This reaction is analogous to the widely used procedure for immobilizing stationary phases in open tubular colunms. Few practical applications have been demonstrated. 

The formation of a highly reactive nitrene can be used for immobilization of a polymer. The in-situ crosslinking of polymers is induced by exposure to UV light (350 nm) of polymers prepared by free-radical polymerization of the desired monomer to which a pyridinium ylid-type monomer is added in small amounts. Depending on the final product requirements, more than one monomer can be incorporated. This flexibility allows one to tailor a process in a very simple manner. The immobilization of reactive polymer on various surfaces produces a template from which numbers of separation can be performed ion exchange, reverse phase, affinity, or chiral chromatography. The support can also be used in product preparation such as DNA/peptide synthesis. 

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