Free-Radical Grafting by the Chain-Transferring Technique

Free-Radical Grafting by the Chain-Transferring Technique 

This technique is probably one of the simplest ways to form graft copolymers. It consists of carrying out free-radical polymerizations of monomers in the presence of polymers preformed from different monomers. A prerequisite for this synthesis is that the active sites must form on the polymeric backbones during the course of the reactions. Ideally, this occurs if the steps of initiations consist only of attacks by the initiating radicals on the backbones  

Propagations then proceed from the backbone sites  

Terminations can take place in many ways. Of course, termination by combination will lead to crosslinked insoluble polymers and that is undesirable. An ideal termination takes place by chain transferring to another site on a polymer backbone to initiate another chain growth. 

The above, however, is an ideal picture. In reality, the efficiency of grafting by this technique depends upon the following  

---