Telechelic reaction with oxygen

The technique of the sulfur coupling reaction can be used also to prepare multiblock polymers. The technique of deactivation of carbanionic polymer with oxygen or sulfur is able to yield numerous interesting organic compounds such as novel macromolecular initiators, new macromolecular additives, and telechelic polymers. Finally, the coupling reactions can be used to build block polymers. 

Boutevin [2], in his review on Telechelic oligomers by radical reactions developed the categories of functional initiators, i.e., diazoic compounds, hydrogen peroxide, and oxygenated substances. He examined the different reactivities and combinations of such initiators with monomers in order to synthesize telechelic oligomers. Boutevin [2] also summarized the monomers able to totally recombine or to avoid termination by disproportionation. He showed a quantitative amount of recombination only for styrene, acrylates, dienes, and acrylonitrile [31-33]. 

To get the diiodo telechelic structure, the authors used iodoform and methylene iodide as degenerative CTAs. SET involves the production of radical ions generating free radicals and anions or cations. Iodoform and methylene iodide can be activated both by degenerative transfer mediated by the growing PVC radicals and by SET. The reaction may be catalyzed by sodium dithionite (Na2S204). These catalyzed reactions allow the suppression of side reactions but also the scavenging of oxygen. The LRP of vinyl chloride resulted in diiodo PVC with Mn of 6000- 10 000 g mol 1 and with PDI of about 1.6. 

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