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Module 1: Properties and Structure of Matter1.1 Properties of Matter
1.2 Atomic Structure and Atomic Mass
Module 2: Introduction to Quantitative Chemistry2.1 Chemical Reactions and Stoichiometry
2.2 Mole Concept
2.3 Concentration and Molarity
2.4 Gas Laws
Module 3: Reactive Chemistry3.1 Chemical Reactions
3.2 Predicting Reactions of Metals
3.3 Rates of Reactions
Module 4: Drivers of Reactions4.1 Energy Changes in Chemical Reactions
4.2 Enthalpy and Hess's Law
4.3 Entropy and Gibbs Free Energy
Module 5: Equilibrium and Acid Reactions5.1 Static and Dynamic Equilibrium5 Topics
5.2 Factors that Affect Equilibrium2 Topics
5.3 Calculating the Equilibrium Constant2 Topics
5.4 Solution Equilibria
Module 6: Acid/Base Reactions6.1 Properties of Acids and Bases7 Topics
6.2 Using Brønsted–Lowry Theory2 Topics
6.3 Quantitative Analysis1 Topic
Module 7: Organic Chemistry7.1 Nomenclature2 Topics
7.2 Hydrocarbons2 Topics
7.3 Products of Reactions Involving Hydrocarbons
7.4 Alcohols1 Topic
7.5 Reactions of Organic Acids and Bases
7.6 Polymers2 Topics
Module 8: Applying Chemical Ideas8.1 Analysis of Inorganic Substances3 Topics
8.2 Analysis of Organic Substances
8.3 Chemical Synthesis and Design
Working ScientificallyWorking Scientifically Overview1 Topic
Lesson 27, Topic 2
Addition polymers are synthetically produced by adding together unsaturated monomers without the elimination of any atoms.
- Initiator molecule breaks C=C in alkenes (addition reaction). The new substance is a monomer radical, i.e. has one free electron.
- The monomer radical breaks the C=C in another monomer and bonds to it. This, in turn, creates leaves an un-bonded electron across the broken double-bond.
- The polymer propagates in this repeating fashion until an inhibitor molecule bonds to the end of a chain, de-radicalising the polymer and preventing it from further elongating.
Structure of Polymers
Vinyl chloride (chloroethene)
Polyvinyl chloride (PVC)
Uses of Additional Polymers
Low Density – Branched chains; cannot pack closely together.
Low melting point (~80 °C)
Squeezy sauce bottles
Vacuum cleaner tube
High Density – Unbranched, linear chains; packs tightly.
Harder/more rigide than LDPE; less flexible
Garbage bins and buckets
|Piping, sliding, gutters|
Waste water pipes
Resistant to chemical corrosion
Electrical wire insulation
Can be expanded to form styrofoam (low density insulator)
|CD and packaging|
Plastic wine glasses
Foam coffee cups
High melting point (327 °C)
High chemical resistance
Low coefficient of friction
|Non-stick coating for cooking pans|
Anti-corrision container, pipe and medical coatings
Sliding applications, e.g. bearings.
Explanation of Properties
|Polyethylene||LDPE has a high degree of branching, which means is has a low degree of crystallinity and relatively weak dispersion forces. It therefore has a low melting point, is low density and flexible.|
HDPE has a low degree of branching, so a high degree of crystallinity and stronger dispersion forces. This gives it a high melting point, high density and rigidity.
|Polyvinyl chloride||The bulky chlorine side group increases dispersion forces and physical flexibility, resulting in hardness and rigidity.|
Plasticisers may be added along with PVC chains to increase flexibility by weakening the dispersion forces.
|Polystyrene||Bulky benzene substituent increases physical rigidity and strength due to increased dispersion forces.|
|Polytetrafluoroethylene||Fluorine side groups repel, locking the polymer into a linear, elongated helix. Chains align closely to form a crystalline structure, making PTFE hard and rigid due to dispersion forces.|