Telluride-mediated polymerization

Alkyl tellurides appear very effeetive in controlling thermally initiated 

This may reflect the monomeric radical being a much poorer leaving 

The Chemistry of Radical Polymerization Table 9.19 Initiators for Telluride-Mediated Polymerization  

Tclluridc Monomers Tclluridc Monomers Tclluridc Monomers 

One of the major advantages of radical polymerization over most other forms of polymerization, (anionic, cationic, coordination) is that statistical copolymers can be prepared from a very wide range of monomer types that can contain various unprotected functionalities. Radical copolymerization and the factors that influence copolymer structure have been discussed in Chapter 7. Copolymerization of macromonomers by NMP, ATRP and RAFT is discussed in Section 9.10.1. 

An issue in living radical copolymerization is that the conditions for dormant chain activation can vary substantially according to the particular propagating radical. The problem may be mitigated by two factors. 

Although, there are reports on differences in reactivity ratios observed for conventional radical eopolymeri/.ation v.y living radical copolymeri/.alion (ATRP 75 276 546 l8 or RAK D48), most research suggests that reactivity ratios are identical31 8 549 and any discrepancies in composition should be attributed to other factors. 

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In this ca.se, the chain transfer step involves formation of an intermediate adduct. Other examples thought to involve a transfer by homolytic substitution are iodine transfer polymerization (Section 9.5.4) and TERP (telluride-mediated polymerization, Section 9.5.5). 

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