Question

Which of the following are condensation polymers? (1) PAN (2) Neoprene (3) polystyrene (4) Poly (ethylene terephthalate) (a) 1 and 4 only (b) 3 and 4 only (c) 2 and 3 only (d) 4 only

Short answer

(d) 4 only

Step-by-step solution

Understanding Condensation Polymers

Condensation polymers are formed through a condensation reaction, where monomers bond together, losing small molecules such as water or methanol as by-products. It’s important to identify if any of the given polymers are formed through such reactions.

Identifying PAN (Polyacrylonitrile)

Polyacrylonitrile is created through addition polymerization of acrylonitrile monomers. Since it forms by addition, it is not a condensation polymer.

Analyzing Neoprene

Neoprene, a polychloroprene derivative, is synthesized through the polymerization of chloroprene molecules. This is an addition reaction. Therefore, Neoprene is not a condensation polymer.

Evaluating Polystyrene

Polystyrene, formed from the polymerization of styrene, is a result of an addition polymerization reaction. It therefore does not qualify as a condensation polymer.

Examining Poly (ethylene terephthalate)

Poly (ethylene terephthalate), also known as PET, is synthesized through the esterification of ethylene glycol and terephthalic acid. This reaction results in the release of water, making it a classic example of a condensation polymer.

Conclusion

From the analysis above, Poly (ethylene terephthalate) is the only polymer that forms through condensation polymerization. Hence, the correct option is the one that includes only poly (ethylene terephthalate).

Key concepts

Polymerization

Polymerization is a chemical process where small molecules, known as monomers, join together to form a large chain-like molecule called a polymer. There are two primary types of polymerization: addition and condensation. In addition polymerization, monomers link without the loss of any small molecules. This means the monomer's entire molecular structure is retained within the resulting polymer. Examples include PAN (Polyacrylonitrile) and polystyrene. In contrast, condensation polymerization involves repeated reactions between monomers with the loss of small molecules, such as water or methanol. Each monomer contains at least two reactive end groups, allowing them to link and simultaneously lose small molecules. Understanding the difference between these two types is crucial to distinguishing between different kinds of polymers.

Condensation Reaction

A condensation reaction is a vital process in forming many polymers. In this reaction, two monomer units connect, and in the process, they release a small molecule like water. This reaction is particularly important in the formation of condensation polymers. To visualize how it works, consider two different molecules that each have reactive end groups. When these groups react, a bond forms between the molecules, and a small molecule (usually water) is expelled. Key features of condensation reactions include:

• The release of a small by-product like water.
• The requirement of two reactive functional groups.
• The ability to create polymers such as polyesters and polyamides.

The understanding of these reactions is essential, especially when learning about synthetic materials like Poly(ethylene terephthalate), which relies on this chemical process for its creation.

Poly(ethylene terephthalate)

Poly(ethylene terephthalate), commonly known as PET, is a widely used synthetic polymer. This polymer is made through a condensation reaction between ethylene glycol and terephthalic acid. During this process, water molecules are released as a by-product. PET is known for several remarkable properties, including:

• Excellent strength and dimensional stability.
• Resistance to moisture and most solvents.
• Transparency, making it ideal for clear packaging such as bottles.

The use of PET is ubiquitous in the production of plastic bottles and clothing fibers. Its strength and transparency make it a preferred material for many products, facilitating a closer look at real-life applications of condensation polymerization.