Hydride Ion, Proton and Carbocation Transfer to Monomer

Due to the ambident reactivity of sulfur and the steric hindrance at the C atom, back-biting predominantly occurs as an attack of the S atom from the chain on the positively charged S atom (tluophilic attack) at the chain end with the elimination of an olefin  

It has conclusively been shown that, althoi six different isimers can be imagined, only two with specific stereochemistry are formed from trans-1,2-dimethylthiirane  

Transfer and termination reactions may involve a number of different compounds present in the polymerization system these are either added intentionally or present as impurities. The intentionally added compounds, usually chain transfer agents, are used simply either to decrease the molecular weight or to obtain polymers with controlled molecular weights and specific end groups (e.g. hydroxy and carboxy groups) which can then be utilized for further reactions. 

In this section we shall, however, confine ourselves only to those reactfons that involve monomer and polymer. The other transfer and termination reacttons leadii to oligomers of a desired molecular stmcture will be discussed in the second part of 

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