Chemistry Industrial Chemistry PMDC Conceptual Practice
PMDC Verified Question 19 of 41
Why must monomer species participating in linear condensation polymerization possess at least two reactive functional groups?
A
To enable continuous bidirectional chain growth at both ends of each growing macromolecule
B
To prevent the elimination of small byproduct molecules such as water or hydrogen chloride
C
To initiate spontaneous free-radical propagation without external energy input
D
To ensure instantaneous dissolution of the resulting polymer in neutral water
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: To enable continuous bidirectional chain growth at both ends of each growing macromolecule
Concept:

Linear step-growth condensation polymerization requires monomers with a functionality of \(f = 2\) (bifunctional) to build continuous macromolecular chains.

Formula / Reaction:

$$\text{Average Degree of Polymerization (Carothers): } \overline{X}_n = \frac{2}{2 - f\,p}$$

Solution:

  • If a monomer is monofunctional (\(f = 1\)), reaction with another functional group terminates the chain, preventing further propagation.


  • Bifunctionality (\(f = 2\)) ensures that every coupling reaction leaves active functional groups at both chain termini for continuous extension.


Why other options are incorrect:

  • Option B: Condensation reactions inherently eliminate small byproduct molecules.


  • Option C: Step-growth condensation proceeds via functional group chemistry, not free-radical chain mechanisms.


  • Option D: Monomer functionality determines chain length and architecture, not water solubility.

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