Official Correct Choice:
Option C: At least two reactive functional groups (e.g., -OH, -COOH, -NH₂) per monomer molecule
Concept:Step-growth condensation requires polyfunctional monomers (functionality \(f \ge 2\)) capable of forming chemical linkages at two or more positions.
Formula / Reaction:$$n\,\text{A}-\text{R}-\text{A} + n\,\text{B}-\text{R}'-\text{B} \longrightarrow -[\text{R}-\text{AB}-\text{R}'-\text{AB}]_n- + (2n-1)\,\text{xy}$$
Solution:- Bifunctional monomers (diols, dicarboxylic acids, diamines) allow step-wise chain extension from both ends to build high-molecular-weight polymers.
Why other options are incorrect:- Option A: Monofunctional species terminate chain propagation prematurely.
- Option B: Non-polar unreactive frameworks cannot undergo condensation reactions.
- Option D: Carbon-carbon double bonds undergo chain-growth addition polymerization.
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