Q$4$ Cont'd: d$)$ Provide the structure for the chain end group $x$ that would result from chain

termination through the following termination mechanism:

Disproportionation:

Structure of $x=$

Chain end radical recombination:

Structure of $x=$

Hydrogen abstraction:

Structure of $x=$

d$)$ Early in the polymerization at lower conversion of the MVK monomer, the

polymer chains formed are primarily linear. However, close to the end of the

reaction, as most of the monomer is consumed, branched polymers may start

to appear. Propose a possible rationale for the formation of branched polymer

structures $($hint: consider the types of termination reactions that may compete

with polymerization when only little monomer is still present$).$