JEE Main 2022 · 24 June · evening · Single correct · +4 / −1
Which of the following is not an example of a condensation polymer?
- (a) Nylon 6,6
- (b) Dacron
- (c) Buna-N
- (d) Silicone
Answer and solution
Answer (c) Buna-N
Solution
Chemistry ma’am · 3 steps
Ask one question of each polymer: does a small molecule like water leave when the chain grows?
- The test. In a condensation polymer, every new link releases a small molecule such as H₂O or HCl. In an addition polymer, monomers with C=C bonds join end to end and nothing is lost.
Polymer Monomers Small molecule lost? Type Nylon 6,6 hexamethylenediamine + adipic acid yes, H₂O condensation (polyamide) Dacron ethylene glycol + terephthalic acid yes, H₂O condensation (polyester) Buna-N 1,3-butadiene + acrylonitrile no addition (copolymer) Silicone R₂Si(OH)₂ from hydrolysis of R₂SiCl₂ yes, H₂O condensation - Why Buna-N differs. Butadiene (CH₂=CH-CH=CH₂) and acrylonitrile (CH₂=CH-CN) both have C=C bonds. These bonds open up and join directly, so the polymer contains every atom of the monomers.
- So. Buna-N is an addition polymer, so it is the one that is not a condensation polymer. The answer is (c).
The idea to keep. Monomers with C=C bonds give addition polymers. Monomers with two reactive groups such as -OH, -COOH or -NH₂ give condensation polymers and lose water.
Answer from the NTA final answer key. Solution by PrepWiser.