Problem 4 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Which of the following is a condensation polymer? [Main April 10, 2019 (I)] (a) Buna - S (b) Neoprene (c) Teflon (d) Nylon 6, 6

Step-by-Step Solution

Answer

Nylon 6, 6 is a condensation polymer.

Step 1: Understanding Polymers

Polymers are large molecules made up of repeating structural units called monomers. They can be classified based on their formation process into two major categories: addition polymers and condensation polymers.

Step 2: Defining Condensation Polymers

Condensation polymers are formed through a chemical reaction where each time a monomer is added to the growing polymer chain, a small molecule such as water or HCl is released. Nylon 6, 6 is a classic example of a condensation polymer.

Step 3: Identifying the Polymers in Options

Let's examine the options: (a) Buna - S is a copolymer made by the addition polymerization of butadiene and styrene. (b) Neoprene is produced by the polymerization of chloroprene. (c) Teflon is created by the polymerization of tetrafluoroethylene. (d) Nylon 6, 6 is formed by the condensation polymerization of hexamethylene diamine and adipic acid.

Step 4: Choosing the Condensation Polymer

From the analysis, Nylon 6, 6 (option d) is made through a condensation reaction where water is lost during polymer formation, classifying it as a condensation polymer.

Key Concepts

Addition Polymers

Addition polymers are an intriguing type of polymer formed when monomers join together through an addition reaction. In these reactions, monomers combine without forming any by-products. This process typically involves unsaturated monomers, such as alkenes, that contain double bonds.
When these monomers react, the double bonds open up, connecting one unit to the next in a chain formation. Because there are no small molecules released as by-products, the entire monomer mass becomes part of the polymer chain. In the given options, several polymers are formed by this method:

• Buna-S: An addition polymer from butadiene and styrene.
• Neoprene: Another addition polymer, produced from chloroprene.
• Teflon: Created by the polymerization of tetrafluoroethylene.

These examples clearly illustrate the efficient and waste-free nature of addition polymerization.

Monomers

Monomers serve as the essential building blocks for forming polymers. They are small molecules that can bond with others of the same kind to form a polymer. Each polymer is characterized by the type of monomers used and the method of polymerization applied.
For instance, if you consider the examples already mentioned,

• In Buna-S: The monomers involved are butadiene and styrene.
• For Neoprene: The monomer used is chloroprene.
• In Teflon: The monomer is tetrafluoroethylene.

The diversity in polymers arises from the use of various monomers and how they are combined to form long chains. Their specific arrangements and bonds dictate the final properties of the polymer.

Nylon 6,6

Nylon 6,6 is a fascinating example of a condensation polymer, quite different from addition polymers. It is created through the polycondensation of hexamethylene diamine and adipic acid.
In this process, each time a bond forms between the reactive ends of these monomers, a molecule of water is released. This release is a characteristic feature of condensation polymerization. Nylon 6,6 is known for its strength and durability, often used in textiles and engineering applications. It is created when:

• Hexamethylene diamine provides the amine group –NH2.
• Adipic acid provides the acid group –COOH.

The reaction between these two functional groups forms an amide bond (-CONH-), releasing water, and creating the long and strong polymer chains for which nylon is renowned. As such, nylon 6,6 illustrates the typical traits of a condensation polymerization process.