Question

Choose the correct option that best correlates the graphs with the polymerization methods.

• A. P – living polymerization; Q – chain growth; R – step growth
• B. P – chain growth; Q – living polymerization; R – step growth
• C. P – step growth; Q – living polymerization; R – chain growth
• D. P – living polymerization; Q – step growth; R – chain growth

Hint:

Remember: - Step growth $\Rightarrow$ high MW only near 100% conversion. - Chain growth $\Rightarrow$ high MW chains appear early and remain constant. - Living polymerization $\Rightarrow$ $M_n$ grows linearly with conversion.

Answer 1

The Correct Option is B

Step 1: Recall the relation between $\overline{M_n$ (number-average molar mass) and % conversion for different polymerizations.}
- In living polymerization: $M_n$ increases linearly with conversion, because chains grow steadily without termination. $\Rightarrow$ Graph P (straight, proportional rise).
- In chain growth polymerization: high molecular weight chains form almost immediately at very low conversion, and then $M_n$ stays nearly constant as conversion increases. $\Rightarrow$ Graph Q (flat plateau).
- In step growth polymerization: only dimers, trimers, oligomers form early; high molecular weight polymers appear only near full conversion (>95%). $\Rightarrow$ Graph R (sharp rise only at high conversion).
Step 2: Match graphs with labels.
- P $\Rightarrow$ living polymerization
- Q $\Rightarrow$ chain growth polymerization
- R $\Rightarrow$ step growth polymerization
Step 3: Select correct option.
This corresponds to option (A). Final Answer: \[ \boxed{\text{(A) P – living polymerization; Q – chain growth; R – step growth}} \]