Back to: Organic Chemistry 500 Level
Welcome to class!
It is wonderful to have you back again. Today we are focusing on a topic that touches every part of daily life: Organic Chemistry of Polymers. From plastic chairs in our homes, to rubber tyres on our roads, to the nylon bags in the market, polymers are everywhere. Understanding how they are formed and how they behave equips you with knowledge that links organic chemistry to real-world materials science.
Organic Chemistry of Polymers
Imagine beads threaded on a string. Each bead represents a repeating small molecule (a monomer), and the whole necklace represents a polymer. Just as the beauty of the necklace comes from the arrangement of beads, the properties of a polymer depend on the structure and type of its repeating units. Organic chemistry of polymers studies how these long chains are formed, modified, and used in technology and society.
Basic Concepts in Polymer Chemistry
Monomers: Small organic molecules that join together. Examples: ethene, styrene, methyl methacrylate.
Polymers: Large molecules made by repeating monomer units. Examples: polyethylene, polystyrene, polyvinyl chloride (PVC).
Degree of Polymerisation: The number of repeating units in a chain. Higher degree means higher molecular weight.
Types of Polymerisation
Addition Polymerisation
Involves unsaturated monomers (like alkenes).
Example: Ethene molecules join to form polyethylene.
Everyday link: The polythene bags used in shops.
Condensation Polymerisation
Two different monomers join with the elimination of a small molecule (often water or HCl).
Example: Formation of nylon from diamine and dicarboxylic acid.
Analogy: Like cooking jollof rice where water vapour escapes as ingredients combine into a new dish.
Classification of Polymers
Natural Polymers: Proteins, cellulose, natural rubber.
Synthetic Polymers: Plastics, nylons, PVC.
Semi-synthetic Polymers: Modified natural polymers, e.g., cellulose acetate.
Structure and Properties
Linear Polymers: Chains arranged end to end (e.g., high-density polyethylene).
Branched Polymers: Chains with side groups (e.g., low-density polyethylene).
Cross-linked Polymers: Chains linked together, making them rigid (e.g., Bakelite).
The structure dictates properties such as strength, flexibility, solubility, and melting point. For instance, the rubber sole of a shoe is flexible because of the nature of its polymer chains.
Applications of Polymers
Everyday Life: Plastics, packaging, fabrics, footwear.
Medicine: Biodegradable polymers used in sutures, drug delivery systems.
Construction: PVC pipes, insulation materials.
Technology: Conducting polymers in electronics and solar panels.
Environmental Concerns and Solutions
Polymers, especially plastics, pose waste management challenges. Nigeria, like many countries, struggles with plastic pollution. Solutions include:
Recycling.
Developing biodegradable polymers.
Encouraging reduced usage of single-use plastics.
Summary
- Polymers are large molecules made of repeating monomer units.
- Polymerisation occurs by addition or condensation mechanisms.
- Polymers can be natural, synthetic, or semi-synthetic.
- Structure (linear, branched, cross-linked) determines properties.
- Applications cover daily life, medicine, construction, and technology, but environmental concerns remain.
Evaluation
- Define a polymer and give two examples.
- Differentiate between addition and condensation polymerisation.
- Explain how polymer structure affects its properties.
- State two applications of polymers in medicine.
- Suggest one way to reduce the environmental problem of plastics.
You are doing excellently well! By mastering the chemistry of polymers, you are seeing how organic chemistry connects to the materials shaping modern life. With this knowledge, you are capable of developing sustainable solutions for Nigeria, Africa, and the wider world. Keep learning with Afrilearn—you are building both knowledge and impact.