Question

Which of the following statements is not true?
A. Chain growth polymerization involves homopolymerization only
B. Chain growth polymerization includes both homopolymerism and copolymerization
C. Nylon 6 is an example of step-growth polymerization
D. Step growth polymerization requires a bifunctional monomer

Answer 1

Hint: In order to answer this question, you need to recall the mechanism chain growth polymerization and step growth polymerization. Homopolymerization involves the formation of addition polymers by the polymerization of a single monomeric species. Copolymerization involves cross linking of more than one species of monomer.

Complete step by step answer:
The chain growth polymerization technique involves the addition of unsaturated monomer molecules onto the active site on a growing polymer chain one at a time.
There are only a limited number of active sites during the polymerization which gives this method it’s key characteristics.
Chain polymerization has three key steps.
The first step is chain initiation which is the process of generating a chain carrier in a cabin polymerization. Chain initiation can be of various types namely thermal initiation, high energy initiation, chemical initiation etc.
Second step is chain propagation involves addition of one monomer molecule on the active center of the growing polymer molecule to form a new polymer molecule which is one repeat unit longer with a new active center.
Third step is the chain termination in which the active center disappears, resulting in the termination of chain propagation.
Chain growth polymerization does not involve the polymerization of more than one monomer species.
Thus, we can conclude that chain growth polymerization does not include copolymerization. Chain growth polymerization involves only homopolymerization.

Therefore, the statement B is wrong .

Note:
Step growth polymerization mechanism involves the polymerization of bi-functional or multifunctional monomers. The mechanism of a step growth mechanism can be visualized as a group of people holding their hands forming a human chain with each person having two sites (hands).
Nylon 6 is synthesized using caprolactam which is a bi-functional compound and follows step growth mechanisms to polymerize.