Problem 9 - Chemistry in 30 days

Question

Amongst the following, a homopolymer is (a) Nylon \(\begin{array}{llll}\text { (b) Bakelite (c) Polythene (d) } & \text { Dacron }\end{array}\)

Step-by-Step Solution

Answer

Polythene is a homopolymer.

Step 1: Understand the Definition of a Homopolymer

A homopolymer is a polymer that is made up of only one type of monomer unit repeated throughout the chain. It has a repeating unit of a single kind of monomer.

Step 2: Review the Given Options

Review the options provided: (a) Nylon, (b) Bakelite, (c) Polythene, and (d) Dacron. Determine the monomer composition for each of these polymers.

Step 3: Analyze Each Polymer

- **Nylon:** It is a copolymer made from two different monomers, usually a diacid and a diamine. - **Bakelite:** It is a phenol-formaldehyde resin, which is also formed from different monomers. - **Polythene (Polyethylene):** It is composed of a single repeating unit, ethylene (C2H4), making it a homopolymer. - **Dacron (Polyester):** It is made from two types of monomers, a dicarboxylic acid and a diol.

Step 4: Identify the Homopolymer

Based on the composition, polythene (polyethylene) is the only polymer from the options that consists of a single type of monomer (ethylene), making it a homopolymer.

Key Concepts

Polymer Chemistry

Polymer chemistry is a fascinating field of science that focuses on the study of polymers. Polymers are large molecules composed of repeating structural units known as monomers. These monomers are bonded together in long chains to form the polymer. The unique properties of polymers, such as their elasticity and toughness, arise from the way monomers link together and the lengths of these chains.

Some common qualities of polymers include:

• High molecular weight due to large chain length
• Varied properties based on monomer types and arrangements
• Ability to form complex structures

Polymer chemistry involves understanding these building blocks and how they can be manipulated to create materials with desirable characteristics. The field covers everything from the basic chemical reactions used to synthesize polymers to the applications for these materials in real-world scenarios. It's both an intricate and highly creative science, blending chemistry with aspects of physics and engineering.

Monomers

Monomers serve as the fundamental building blocks of all polymers. They are small molecules that can join together with other similar molecules to form a polymer. The nature of a monomer greatly influences the properties of the polymer it forms. This is because the chemical structure of the monomer determines how they connect in chains and what properties those chains have.

The characteristics of monomers include:

• Small size and simple structure
• Reactive functional groups that allow bonding
• Capability to form covalent bonds with other monomers

Think of monomers as the individual links in a necklace, where each link can connect with another to form the entire piece. By choosing different monomers or modifying them, chemists can create a wide variety of polymers with customized properties and functions to suit specific applications.

Polyethylene

Polyethylene, also known as polythene, is one of the simplest and most widely used polymers. It is a homopolymer formed by polymerizing ethylene, a small molecule consisting of two carbon atoms double-bonded to each other and two hydrogen atoms bonded to each carbon. This simple structure is repeated many times to form a long chain of polyethylene.

Polyethylene is known for several key properties:

• Lightweight yet highly durable
• Excellent chemical resistance
• Flexible and easy to process

Thanks to these characteristics, polyethylene has a wide range of applications in daily life, such as in plastic bags, bottles, containers, and even in the insulation of wires and cables. Its simplicity in composition contributes to its versatility and has made it a staple in the world of thermoplastic materials.

Polymer Classification

In polymer chemistry, classification is essential to understanding the diverse nature of polymers. Polymers can be classified based on various criteria, and one of the most common methods is their composition, particularly looking at whether they are homopolymers or copolymers.

Some key polymer classification types include:

• Homopolymers: Polymers that consist of a single type of monomer. Polyethylene is a classic example, as it is made entirely from ethylene monomers.
• Copolymers: Polymers formed from two or more different types of monomers. For example, Nylon is a copolymer made from a diamine and a diacid.
• Thermoplastics and Thermosets: Thermoplastics can be melted and reshaped, while thermosets form permanent chemical bonds and cannot be remolded once cured.
• Natural and Synthetic Polymers: Natural polymers include materials like silk and wool, whereas synthetic polymers include man-made materials such as plastics and Teflon.

This classification helps in predicting the behavior of polymers in different conditions and aligning them with suitable applications in industries ranging from packaging to automotive to biomedical fields.