Polymers and Polymerisation

Active learning helps students visualize the invisible molecular changes in addition polymerisation. By handling physical models and testing real materials, students replace abstract formulas with concrete understanding of how monomers link and why polymers behave as they do.

• Year 11
• Chemistry
• 4 activities
• 25 min–45 min

Learning Objectives

1. Explain the mechanism of addition polymerisation, illustrating the breaking of carbon-carbon double bonds and the formation of a polymer chain.
2. Compare and contrast the structures of different addition polymers based on their corresponding alkene monomers.
3. Analyze the environmental impact of common addition polymers, identifying specific challenges related to their persistence and fragmentation.
4. Evaluate the effectiveness of different disposal methods for addition polymers, such as recycling and incineration, in mitigating environmental harm.
5. Identify the repeat unit in a given addition polymer structure and deduce the structure of its monomer.

Case Study Analysis

⏱ 30 min·Pairs

Modelling: Monomer Chain Building

Provide paper cutouts of monomers with Velcro on double bond sites. Students link them to form polymer chains, label repeat units, and compare chains from different alkenes like ethene and chloroethene. Discuss how chain length affects properties. Wrap up with drawings for portfolios.

Prepare & details

Explain the process of addition polymerisation.

Facilitation Tip: During Monomer Chain Building, circulate with a checklist to ensure each pair correctly forms the repeat unit before adding more monomers to the chain.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 45 min·Small Groups

Investigation: Polymer Properties Testing

Supply samples of polythene, polypropene, and polystyrene. Groups test tensile strength by stretching, response to heat with Bunsen burners, and solubility in solvents. Record data in tables and link properties to monomer structure and uses.

Prepare & details

Differentiate between different types of polymers based on their monomers.

Facilitation Tip: For Polymer Properties Testing, assign roles so every student observes and records data, preventing one person from doing all the work.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Formal Debate

⏱ 40 min·Whole Class

Formal Debate: Disposal Solutions

Divide class into teams to research and argue for or against methods like recycling, biodegradable alternatives, or chemical breakdown. Each team presents evidence on environmental impact, then votes on best solution with justifications.

Prepare & details

Evaluate the environmental challenges associated with polymer disposal.

Facilitation Tip: In the Debate on Disposal Solutions, provide a timer for each speaker and a visible scorecard so students practice concise, evidence-based arguments.

Setup: Two teams facing each other, audience seating for the rest

Materials: Debate proposition card, Research brief for each side, Judging rubric for audience, Timer

• Analyze
• Evaluate
• Create
• Self-Management
• Decision-Making

Case Study Analysis

⏱ 25 min·Pairs

Demo Follow-Up: Slime Synthesis

Demonstrate cross-linked polymer formation using PVA glue and borax. Students in pairs make their own slime, vary ratios, and test elasticity. Connect to addition polymerisation by discussing monomer links and real-world applications like adhesives.

Prepare & details

Explain the process of addition polymerisation.

Facilitation Tip: After Slime Synthesis, ask students to compare the slime’s properties to real polymers, linking viscosity and cross-linking to industrial applications.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Teaching This Topic

Teach addition polymerisation by starting with familiar materials students can manipulate, like paper clips or beads, before moving to molecular models. Avoid rushing the concept of the repeat unit—students need time to see that the polymer chain is made of identical segments. Research shows that drawing the process by hand, even roughly, improves retention more than passive note-taking, so include quick sketching tasks in each activity.

What to Expect

Students will confidently connect monomer structures to polymer chains, explain the role of the C=C bond, and evaluate environmental impacts of synthetic polymers. Success looks like accurate drawings, thoughtful testing, and evidence-based discussions about polymer disposal.

Watch Out for These Misconceptions

Common Misconception

During Monomer Chain Building, watch for students who treat the polymer as a random tangle of monomers rather than a precise sequence of linked repeat units.

What to Teach Instead

Ask students to pause after forming the first three monomers and explain how the repeat unit is preserved in each link. Have them label the carbon backbone and double bond site on their chain.

Common Misconception

During Polymer Properties Testing, watch for students who assume all plastics degrade quickly because they confuse synthetic polymers with natural materials like starch.

What to Teach Instead

Before testing, have students predict which plastics will degrade fastest and justify their choices. After results, revisit the predictions to highlight the persistence of C–C bonds in addition polymers.

Common Misconception

During Monomer Chain Building, watch for students who draw the polymer chain with the same structure as the monomer, including the double bond.

What to Teach Instead

Provide molecular model kits and ask students to break the double bond physically before forming the chain. Have them redraw the monomer as the repeat unit minus the double bond on their worksheet.

Assessment Ideas

Quick Check

After Monomer Chain Building, provide the structures of ethene and propene. Ask students to draw the corresponding addition polymer and label the repeat unit. Collect work to check that they have shown the carbon-carbon single bond in the polymer backbone.

Discussion Prompt

After the Debate on Disposal Solutions, facilitate a class discussion where students compare the pros and cons of landfill, incineration, and recycling methods. Listen for evidence linking polymer structure to disposal challenges and environmental impact.

Exit Ticket

During Slime Synthesis, ask students to write on an index card the name of one common addition polymer, its monomer, and one significant environmental problem associated with its disposal. Collect these to gauge understanding of the link between polymer type and impact.

Extensions & Scaffolding

• Challenge: Ask students to research a biodegradable polymer and compare its monomer structure and environmental benefits to a common addition polymer.
• Scaffolding: Provide a partially completed polymer chain template for students to finish during Monomer Chain Building, highlighting where the double bond was.
• Deeper exploration: Have students design an experiment to test the effect of temperature on polymer degradation using a variety of plastic samples and a controlled heat source.

Key Vocabulary

Monomer	A small molecule that can react with other identical or similar molecules to form a larger polymer molecule. In addition polymerisation, monomers typically contain a carbon-carbon double bond.
Polymer	A large molecule made up of many repeating smaller units called monomers, linked together by covalent bonds. Addition polymers are formed by the direct joining of monomers.
Addition Polymerisation	A type of polymerisation reaction where unsaturated monomers (containing double or triple bonds) add to one another in such a way that the polymer contains all the atoms of the monomer unit. No byproducts are formed.
Repeat Unit	The specific arrangement of atoms that repeats itself throughout the polymer chain. It is derived from the monomer structure after the double bond has opened.
Alkene	An unsaturated hydrocarbon containing at least one carbon-carbon double bond. Alkenes like ethene and propene are common monomers for addition polymers.