Question

What's the difference between transfer to monomer and transfer to polymer in cationic polymerization reactions? What influences which one of these dominates?

Answer 1

Chain transfer is a process during polymerization reaction by which the active site of a growing polymer chain is transferred to another molecule.

P• + XR → PX + R•

Transfer to monomer. Chain transfer to monomer may take place in which the growing polymer chain abstracts an atom from unreacted monomer existing in the reaction medium. Chain transfer to monomer is especially significant in cationic polymerization.

Chain transfer to monomer determines the theoretical maximum molecular weight that can be achieved by a given monomer.

Transfer to polymer. Chain transfer may take place with an already existing polymer chain, especially under conditions in which a large amount of polymer has formed.

The concentrtaion of the monomer to polymer dominates which one occurs. In the initial stages of the polymerization Transfer to monomer occurs and at the end of the polymerization trnafer to polymer occurs.