How alkenes join into addition polymers and how to draw the repeat unit, condensation polymers such as polyesters, and the natural polymers DNA, proteins, starch and cellulose.
What you will learn
- Draw the repeat unit of an addition polymer from its monomer and back again
- Explain how condensation polymerisation differs from addition
- Name the monomers of DNA, proteins, starch and cellulose
Addition polymers
Many small alkene molecules (monomers) join into one very long molecule (a polymer).
The C=C double bond in each monomer opens and links to the next. Nothing else is made.
To draw the repeat unit: copy the two carbons and their side groups, make the C to C bond single, add a bond out each side through square brackets, and write n.
The polymer is named poly(monomer): ethene makes poly(ethene), propene makes poly(propene), chloroethene makes poly(chloroethene) (PVC).
The side groups never move or change. Only the double bond becomes single.
The rest of this lesson and its 11 practice questions are locked.
In this lesson
- Addition polymers
- Try it: From monomer to repeat unit
- Condensation polymers
- Natural polymers
11 practice questions, marked as you go; about 22 minutes in all.
Key terms
Monomers, Polymer, Condensation polymerisation, Two functional groups, Water, Diol, Dicarboxylic acid, Polyester, Amino acids, Polypeptide
In this unit: Organic chemistry
Crude oil and the alkanes, combustion and cracking, then alkenes, alcohols, carboxylic acids, esters and polymers for separate Chemistry, with the formula and mass calculations that go with them.