Past exam of the chemistry course of the year 4 of the natural sciences course of the University of Cambridge / 2022 / Paper 1 / 1 / c / Solution

For the ideal equimolar step-growth polymerization, $p=0.5$ givesThis counts individual starting molecules, so it is only roughly one diamine–diester pair per average chain, rather than a long polymer. In a successful radical polymerization, many monomers normally add between initiation and radical termination. The styrene–maleic anhydride copolymer in (iv) therefore has the larger expected degree of polymerization.

Conversion alone does not specify the radical-chain length: the conclusion assumes ordinary polymer-forming conditions, rather than arbitrarily high initiator concentration or extremely strong chain transfer in chain polymerization.