Welcome
to
World University Of Bangladesh
Department of TE, CE and EEE
Course title: Chemistry
Presented by
Dr. Jahida Binte Islam
Senior Lecturer in Chemistry
Basic Science Division
Topics: Polymer Chemistry
Definition of Polymer, Mer, Monomer
Basic criteria that monomers generally fulfill in products high
polymersClassification of Polymer-
Addition polymer & Condensation polymer
Distinguish between addition and condensation polymerization
Application of polymers
Polymer chemistry
Sub-discipline of chemistry that focuses on the structures of
chemicals, chemical synthesis, and chemical and physical properties
of polymers and macromolecules.
A polymer always consists of thousands of repeating monomers units.
However a macromolecule is a giant molecule which may or may not
contain monomer units.
Polymer
Definition: Polymer is a large molecule built up by the repetition of small and
simple chemical units and contains high molecular Weight.
For example: CH2- CH2- CH2- CH2-Polyethylene
Mer: The repeating unit in a polymer chain is known as mer. It is a simple
chemical entity and does not exist in normal condition.
For example: In polyethylene the repeating unit is -CH2-CH2-,
which is not existence in normal condition. Thus, -CH2-CH2- is a
mer.
Monomer: The simple compounds from which polymers are obtained are
called monomers.
For Example: n CH2=CH2 → [-CH2-CH2-CH2-CH2-]n
Monomer Polymer
Classification of Polymer
Classify polymers according to their physical properties--Polymers are classified on the basis of their physical properties or on the action
of heat are on three categoriesi. Thermoplastics
ii. Elastomers
iii. Thermosetting
Classify polymers on the basis of structural units---
Polymers are classified on the basis of structural units are two categoriesi. Homo polymers
ii. Copolymers
Classify polymers on the basis of mode of synthesis--Classify polymers on the basis of mode of synthesis are two categoriesi. Addition polymers
ii. Condensation polymers
Addition polymer & Condensation polymer
Addition polymers: The polymerization process in which the formation of
polymers
from
monomers without the loss of Small molecules, i.e.; in which molecules of monomers are simply
added together is called additional polymerization and such polymers are known as addition
polymer.
For example-- The molecules of ethylene monomer can add on two form
polyethylene, in
which, the structural identity of ethylene is retained.
n CH2=CH2 → [-CH2-CH2-CH2-CH2-]n
Condensation polymers: The polymerization process in which the formation of polymers
from the poly functional monomers of organic molecules with the elimination of some small
molecules such as, water, HCl, NH3, etc. is called
condensation polymerization and the
product is called condensation polymer.
For Example:
n HO-CH2-CH2-OH + n HO-C-CH2-C-OH → HO-(-CH2-CH2-O-C-CH2-C-O)n-H + (n-1)H2O
Ethylene glycol
Malonic acid
Distinguish between addition and condensation
polymerization1
Polymers are formed by addition 1
reaction without elimination of any
species.
Polymers are formed by the indentation of two
or more monomers with the elimination of
small molecules such as –H2O, NH3, HCL etc.
2
It is a rapid process.
It is very slow process.
3
Addition polymerization proceeds by 3
chain mechanism.
Condensation polymerization proceed by stepwise
inter molecular condensation.
4
Polymers of high molecular weight 4
obtained by additional polymerization.
Low molecular weights polymers are obtained by
condensation polymerization.
5
Chain length is independent of time.
Chain length is dependent on time.
6
The rate of addition polymerization 6
reaction is controlled by the addition of
inhibitor or retarder.
2
5
The rate of condensation polymerization reaction
is not controlled by such chemicals.
Application of polymers:
Medicine: Many biomaterials, especially heart valve replacements and blood
vessels are made of polymers like Dacron, Teflon and polyurethane.
Consumer Science: Plastic containers of all shapes and sizes are light weight and
economically expensive than the more traditional containers. Clothing, floor
coverings, garbage disposal bags and packaging are other polymer application.
Industry: Automobile parts, windshield for fighter planes, pipes, tanks, packing
materials, insulation, wood substitutes, adhesive, matrix for composites and
elastomers are all polymer application used in the industrial market.
Sports: Playground equipment, various balls, golf clubs, swimming pools and
protective helmets.