Download Polymers - Yafi Zayyat

Polymers
The word ‘polymer’ comes from the Greek words poly
(meaning ‘many’) and meros (meaning ‘parts’).
Yafi Zayyat
What is a polymer?
A substance that
has a molecular
structure
consisting chiefly
or entirely of a
large number of
similar units
bonded together
How is a Polymer formed?
A polymer is
formed by
polymerization.
Polymerization is
the process in
which monomers
combine
chemically to
produce a
polymer.
What is a Monomer?
A monomer is a
molecule that can
be bonded to
other identical
molecules to form
a polymer.
 For example
A + A + A + A  -A-A-A-Ae.g- Ethene= Poly(ethene)
How many types of
polymerization are there?
There are two types of polymerization:
 Addition
 Condensation
Addition polymerization
Addition polymerization is the formation of successive
links between small units called monomer molecules
containing a C=C double bond to form a a long chained
macromelcule
For example:
Polyethene (sometimes called polythene) is a polymer
made from ethene.
Polymerization
Polymer
Condensation polymerization
Condensation polymerization is the formation of successive links
between small units called monomer molecules to form a long
chained macromolecule ( polymer ) and a small molecule ( usually
water).
For example:
Dicarboxylic acid + Diamines
Nylon ( polyamide ) + water
Types of condensation polymers
What decides the properties of a
polymer?
 Stronger attractive forces between chains = stronger, less
flexible polymer.
 Chains able to slide past each other = flexible polymer .
Drawing polymers – shorthand
formulae
Polymers contain thousands of molecules, so how can their
structures be easily drawn?
Part of the polymer molecule can be drawn
A better way is to show a shorthand formula:
The ‘n’ means that the polymer
contains a very large number of
the repeating unit shown in the
brackets.
Examples of polymers
 Polythene – plastic bags, bottles, bowls
Very cheap and strong. Easily moulded.
 Polypropene – crates, ropes, carpets.
Forms strong fibres. Has high elasticity.
 Polystyrene – radio cases, foam packaging.
Cheap and easily moulded.
Can be expanded into foam.
Four types of organic polymers
1. CARBOHYDRATES – glucose, bread, pasta
CARBO(C) – HYDRATE(H2O)
2. PROTEINS – muscle, meat, hair, nails
3. LIPIDS – fat, oil, butter
4. NUCLEIC ACIDS – DNA, RNA
Carbohydrates

Monomer- the simple sugars, Glucose, sucrose, fructose (and many others)

Polymer - The complex carbohydrates.
 Starch and Cellulose are long chains of simple sugars
Proteins
 Monomer- amino
acids
 Polymer- polypeptide
Nucleic Acid
DNA (a nucleic
acid) is a polymer
DNA is made of
monomers called
nucleotides
Longer chains make stronger
polymers.
• Critical length needed
before strength
increases.
• Hydrocarbon polymers
average of 100
repeating units
necessary but only 40
for nylons.
• Tensile strength
measures the forces
needed to snap a
polymer.
Review
 Polymers are made up of monomers
Polymerization;
 Addition- produces only a polymer
 Condensation- produces a polymer and small moclecule
usually water.
Four types of organic polymers
 Proteins
 Carbohydrates
 Nucleic acids
 lipids