Download Chapter 2 polymers

Chapter 2- Polymer Chemistry
2.1 Introducting Polymers
Monomer: the smallest repeating unit of a polymer
(propene in polypropylene).
Polymer: a long chain molecule made up of many small
identical units (monomers).
Polymerization: process of linking monomer units into a
polymer. Can be accomplished by addition or condensation
reactions.
Homopolymer: a polymer made of only a single type of
monomer
Copolymere: are polymers made of two or more types fo
monomers
Natural Polymers
Nature produces a variety of polymers.
 They are built by an organism.
 Examples are : Silk, natural rubber, starch,
chitin, proteins,

Synthetic Polymers
Usually produced from plant material or
petrochemicals
 Examples include: Nylon, Kevlar, non-stick
coating (fluoropolymers), polyester, tires

Synthetic Polymers involve 3
stages in the polymerization
process
1 Initiation- removes a part of the monomer
to make it want to bond with another
monomer
2 Propagation- the process keeps going
3 Termination- a chemical is used that
causes the monomers to stop joining
together
2.2 Synthetic Addition Polymers

Addition polymerization: a reaction in
which unsaturated monomers combine
with each other to form a polymer.

A reaction where monomers with double
bonds are joined together through
multiple addition reactions to form a
polymer
Properties of a polymer are determined
by the properties of its monomers,
which may include functional groups
such as alkyl groups, halides, aromatic
groups and alcohols.
Examples of Addition Polymers

Teflon, polypropylene, polyester,
polyethylene (pop bottles, grocery
bags), polystyrene (packing material),
Plexiglas, polyvinyl chloride (vinyl),
natural rubber, etc

Example Polyvinyl Chloride

Example Polystyrene
Plastics

A polymer that retains its shape after
being heated under pressure and
subsequently cooled.

Plastics tend to be:
◦ Unreactive
◦ Flexible in Shape
◦ Vary in hardness
Polymer Cross-Linking
Cross-linking arises when functional
groups on a chain can interact.
 The softness of a plastic is related to the
amount of cross-linking.
 The greater the level of cross-linking, the
more heat resistant a polymer becomes

Work
Pg. 83 # 1-3
 Pg. 87 # 1-3
 Pg. 93 # 1-4

2.4 Synthetic Condensation Polymer
Condensation polymerization: a reaction
in which two different monomers react at
the functional group to form a polymer.
 Generally a reaction where two monomers
are joined to form a unit called a dimer.
 A dimer generally consists of an ester or
amide linkage.
 If a chemical is bi-functional (having two
different functional groups) it can form a
condensation polymer with itself.

Question what types of chemicals
do we need to use to get the
dimers?
◦ Polyamide
 A dicarboxylic acid and diamines
◦ Polyester
 A diacarboxylic acid and dialcohols
Condensation Reaction
With two different molecules:
With one type of molecule:
Polyester
The Formation of Dacron
Formation of Nylon 6,6
Work
Pg. 98 # 1
 Pg. 99 # 1-6
