Question

In a set of copolymerization reactions, the following monomer reactivity ratios (\(r_1\) and \(r_2\)) were found for different cases. 

Which option(s) correctly identify/identifies the type of copolymerization corresponding to each Case?

• A. P- Ideal copolymerization; Q- Azeotropic copolymerization; R- Block copolymerization
• B. P- Ideal copolymerization; Q- Azeotropic copolymerization; R- Alternating copolymerization
• C. P- Block copolymerization; Q- Ideal copolymerization; R- Alternating copolymerization
• D. P- Ideal copolymerization; Q- Block copolymerization; R- Azeotropic copolymerization

Hint:

The reactivity ratios \(r_1\) and \(r_2\) determine the type of copolymerization. When the ratios are close, ideal copolymerization occurs; when they are both low, azeotropic copolymerization occurs; and when there is a significant disparity, block copolymerization is observed.

Answer 1

The Correct Option is A, C

In this question, we need to analyze the given reactivity ratios (\(r_1\) and \(r_2\)) to determine the type of copolymerization for each case. The reactivity ratios tell us about the tendency of each monomer to react with the other. Based on these values, the following observations can be made:
- Ideal copolymerization (P): In ideal copolymerization, the monomer reactivity ratios \(r_1\) and \(r_2\) are typically close to each other, indicating that the monomers have similar tendencies to react with each other. 
In Case I, we have \(r_1 = 0.1\) and \(r_2 = 10\), which shows a large disparity between the reactivity ratios. However, this does not imply extreme reactivity, suggesting that this case corresponds to ideal copolymerization.
- Azeotropic copolymerization (Q): Azeotropic copolymerization occurs when the reactivity ratios are both very low (less than 1), causing the copolymerization to proceed with little preference for one monomer over the other. 
In Case II, the reactivity ratios \(r_1 = 0.003\) and \(r_2 = 0.02\) are very low, which is typical for azeotropic copolymerization.
- Block copolymerization (R): Block copolymerization occurs when one monomer has a significantly higher reactivity ratio compared to the other, resulting in the formation of distinct blocks of the monomers. 
In Case III, \(r_1 = 3.4\) and \(r_2 = 5.6\), showing a relatively large disparity in the reactivity ratios, which is characteristic of block copolymerization.
Therefore, based on the given reactivity ratios, the correct answer is (A) P- Ideal copolymerization; Q- Azeotropic copolymerization; R- Block copolymerization.