Polymers – GCSE Chemistry

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Introduction

  • Polymers are all around us, found in plastic bags, clothes, non-stick pans, and even in our DNA.
  • Many small molecules called monomers join together to form a large molecule known as a polymer.
  • In this blog, we’ll explore how polymers are formed, their main types, common uses, and how recycling helps reduce pollution from non-biodegradable plastics.

What is a Polymer?

  • A polymer is a large molecule made up of many repeating smaller units called monomers.
  • These monomers link together in long chains through strong covalent bonds.

Polymers can be:

Natural:

Polymers diagram showing natural polymers such as DNA, starch, and protein structures

Synthetic:

Polymers used in everyday materials such as plastic bottles, PVC pipes, and non-stick cookware

What is the Structure of Polymers & How is it Represented?

  • Polymers are made of long chains of repeating units called monomers, linked by strong covalent bonds.
  • These units are identical in structure.
  • Instead of writing the units again and again, they are shown in brackets with lines extending from each side to indicate the continuous chain.

Example:

  • Poly(ethene) has the repeating unit:

Polymers formation diagram showing addition polymerisation of ethene monomers into a polymer chain

Properties:

  • The properties of polymers depend on the chain length and the strength of intermolecular forces.
  • Longer chains and stronger forces make polymers tougher, harder, and more durable.
  • Shorter chains make polymers softer and more flexible.

Classification of Polymers

Polymers can be classified based on how they are formed and where they come from:

Addition Polymers:

  • Addition polymers are formed when many alkene monomers join together.
  • So, the double bonds in the monomers break, and the monomers link in a long chain.
  • In this reaction, no other molecules are produced.

Example:

  • Poly(ethene) is made from ethene (C₂H₄).

Polymers repeating unit diagram showing CH₂–CH₂ structure in polyethene

Condensation Polymers:

  • Condensation polymers are formed when two different monomers, each with two reactive ends, join together.
  • Each time the monomers link, a small molecule such as water (H₂O) is released.

Example:

  • Polyester is made from a diol (–OH at both ends) and a dicarboxylic acid (–COOH at both ends). The polymerisation reaction is:

Polymers condensation polymerisation equation showing polyester formation and water removal

What are the Different Types of Polymers?

  • Polymers come in various types based on the monomers they are formed from and the properties they show.
  • Each type has its own distinct features and uses that make it suitable for different purposes in daily life.

Examples:

Polymers table showing different polymers, their monomers, and common uses

Uses of Polymers

  • Polymers play a major role in our daily lives and in various industries due to their wide range of useful properties such as flexibility, strength, and durability.
  • Below are some important examples of how different polymers are used around us:

Poly(propene)

  • Poly(propene) is strong and flexible, ideal for containers, ropes, buckets, and packaging.

Examples: showing natural polymer rope and synthetic plastic bucket

PVC (Poly(chloroethene))

  • PVC (Poly(chloroethene)) is tough and durable, used for window frames, pipes, flooring, and cable insulation.

Examples: used in window frames and USB cable insulation

PTFE (Teflon)

  • PTFE (Teflon) is non-stick and heat-resistant, used in cookware, waterproof clothing, and machinery coatings.

Non-stick frying pan coated for easy cooking

Polyesters

  • Polyesters are light and strong, used in fabrics, bottles, and packaging films.

Synthetic fabrics and plastic bottles made

Natural Polymers

  • Natural polymers like starch, proteins, and DNA are used in food storage, body repair, and genetic information storage.

Natural including starch and proteins

Frequently Asked Questions

Solution:

A polymer is a large molecule made of many small repeating units called monomers joined together in long chains.

Solution:

Monomers are small molecules, often containing double bonds, that can join together to form polymers.

Solution:

Polymerisation is the chemical reaction where many monomers link together to form a polymer.

Solution:

Addition polymerisation and condensation polymerisation.

Solution:

Alkene monomers with C=C double bonds join to form a polymer, and no other product is formed.

Solution:

They form when two different monomers react together, releasing a small molecule like water each time a bond forms.

Solution:

They differ because of the forces between chains — weak forces make flexible plastics, while strong forces make rigid ones.

Solution:

Polymers are made when many monomers join together; the repeating unit in the polymer has the same atoms as the monomer.

Solution:

They contain strong covalent bonds and are chemically unreactive, so microbes cannot break them down easily.

Solution:

Polymers are used in bags, bottles, pipes, ropes, clothing, coatings, and non-stick cookware.

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