BY- ABU DARDA

2. The word ‘polymer’ comes from the Greek words
poly (meaning ‘many’) and meros (meaning ‘parts’).
Example: POLYBUTADIENE =
(BUTADIENE+ BUTADIENE+......)n
Where n = 4,000
Polymers are very large molecules made when hundreds of monomers join
together to form long chains.

3.  Polymers are complex and giant molecules usually with
carbons building the backbone, different from low molecular
weight compounds.
 The small individual repeating units/moleules are known as
monomers(means single part).
 Imagine that a monomer can be represented by the letter A.
Then a polymer made of that monomer would have the
structure:
-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A
 This kind of polymer is known as HOMOPOLYMER.

4.  In another kind of polymer, two different monomers might
be involved.
 If the letters A and B represent those monomers, then the
polymer could be represented as:
-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A- B-A-B-A
 A polymer with two different monomers is known as a
COPOLYMER / HOMOPOLYMER.

6. Linear
 High Density Polyethylene (HDPE), PVC, Nylon, Cotton
Branched
 Low Density
- Polyethylene (LDPE)
Cross-linked
 Rubber
Network
 Kevlar, Epoxy

7.  Should be inert and compatible with the
environment.
 Should be non-toxic.
 Should be easily administered.
 Should be easy and inexpensive to
fabricate.
 Should have good mechanical strength.

8.  The process by which the monomer molecules are linked to
form a big polymer molecule is called ‘polymerisation’.
 Polymerization is a process of bonding monomer, or
“single units” together through a variety of reaction
mechanisms to form longer chains named Polymer
 As important as polymers are, they exist with monomers,
which are small, single molecules such as hydrocarbons and
amino acids.

9. Addition Polymerization=
When monomers just add on to form the polymer, the process
is called ‘addition polymerisation’. The polymer is the only
product
e.g. Ethylene monomers add on to form
polyethylene. (5 Ethylene monomers)
Polyethylene formation

10. Condensation polymerisation=
 The molecules do not just add on but also undergo some reaction in
forming the polymer, the process is called ‘condensation
polymerisation’.
 Here the two molecules condense to form a polymer.The condensation
takes place between two reactive functional groups, like the carboxyl
group(of an acid) and the hydroxyl group(of an alcohol). While forming
the polymer water molecules also get eliminated.
 In A. P. mol. weight of polymer is roughly equal to that of all monomers,
while in C. P. the mol. weight of polymer is lesser by the weight of simple
molecules eliminated during the condensation process. E.g.
Condensation polymerization diacid diamine.

12.  Polymers which are isolated from natural materials, are called
as ‘natural polymers’.
E.g. : Cotton, silk, wool, rubber.
natural rubber
 Polymers synthesized from low molecular weight compounds, are
called as, ‘synthetic polymers’.
E.g. polyethylene, nylon, terylene.
Polyethylene

14.  A Polymer whose backbone chain is essentially made of
carbon atoms is termed an ‘Organic polymer’.
Examples- cellulose, proteins, polyethylene, nylons.
 A Polymer which does not have carbon atom in their chain
is termed as ‘Inorganic polymer’ .
Examples- Glass and silicone rubber

15.  Some polymer are soften on heating and can be converted into any shape
that they can retain on cooling.
 Such polymer that soften on heating and stiffen on cooling are termed as
`thermoplastic’ polymers.
Ex. Polyethylene, PVC, nylon, sealing wax.
 Polymer that become an infusible and insoluble mass on heating are called
‘thermosetting’ polymers. Plastics made of these polymers cannot be
stretched, are rigid and have a high melting point.

16.  Polymer is shaped into hard and tough utility articles by application of
heat and pressure, is known as ‘plastics’.
E.g. polysterene, PVC, polymethyl methacrylate.
 When plastics are vulcanised into rubbery products exhibiting good
strength and elongation, polymers are known as ‘elastomers’.
E.g. silicone rubber, natural rubber, synthetic rubber, etc.
 Long filament like material whose length is atleast 100 times it’s
diameter, polymers are said to be ‘fibres’.
E.g. Nylon, terylene.
 Polymers used as adhesives, potting compounds, sealants, etc., in a
liquid form are described as ‘liquid resins’.
E.g. Epoxy adhesives and polysulphides sealants.

17. Structure Chemical Name Trade Name or
CommonName
poly(tetrafluoroethylene) Teflon
polypropylene Herculon
polyisobutylene butyl rubber
polyethylene

18. There are three significant reactions that take place in addition
polymerization:

19. INITIATOR:
 A relatively unstable molecule that decomposes into a free
radical. Used to "initiate" a polymer growth reaction. (A
molecule with an unpaired electron, making it highly
reactive).
 The stability of a radical refers to the molecule's tendency to
react with other compounds. An unstable radical will readily
combine with many different molecules. However a stable
radical will not easily interact with other chemical
substances.

20.  The first step in chain polymerization- Initiation involves the
formation of a free radical. Addition can occur at either end of
the monomer. This process is illustrated in the following
animation in which a chlorine atom possessing an unpaired
electron (often indicated as cl-) initiates the reaction.

21. .
 Propagation is the middle step in chain polymerization where
successive monomers are attached to the growing chain. In the
propagation stage, the process of electron transfer and consequent
motion of the active center down the chain proceeds.
 In following reaction(chain), refers to a chain of connected monomers,
and X refers to a substituent group (a molecular fragment) specific to
the monomer. For example, if X were a methyl group, the monomer
would be propylene and the polymer, polypropylene.
 The entire propagation reaction usually takes place within a fraction of
a second.

22.  Termination of reaction is nothing but stop the further
propagation of chain.
 In theory, the propagation reaction could continue until the
supply of monomers is exhausted. Most often the growth of
a polymer chain is halted by the termination reaction.
Termination typically occurs in two ways:
Combination occurs when the polymer's growth is
stopped by free electrons from two growing chains that join
and form a single chain. The following diagram depicts
combination, with the symbol (R) representing the rest of
the chain.
Combination Disproportionatio
n

23. Disproportionation halts the propagation reaction when
a free radical strips a hydrogen atom from an active chain.
A carbon-carbon double bond takes the place of the missing
hydrogen.
- Disproportionation can also occur when the radical reacts
with an impurity. This is why it is so important that
polymerization be carried out under very clean conditions.

24.  There exists a type of addition polymerization that does not
undergo a termination reaction. This so-called "living
polymerization" continues until the monomer supply has
been exhausted. When this happens, the free radicals
become less active due to interactions with solvent
molecules. If more monomers are added to the solution,
the polymerization will resume.
 Uniform molecular weights (low polydispersity) are
characteristic of living polymerization. Because the supply
of monomers is controlled, the chain length can be
manipulated to serve the needs of a specific application.
This assumes that the initiator is 100% efficient.

25.  Mainly used for drug delivery.
 As a coating material
examples: Hydroxyl propyl methyl cellulose(HPMC),
Methyl cellulose,
Propylene glycol.
 As a binders in tabletting granulation
examples: Acacia, Gelatin, Sodium alginate.
 As a disintegrants
examples: starch, HPMC
 As a thickening agent in suspension and ophthalmic preparations
Example: methyl cellulose.
 To form bases in ointments.
 In hard and soft capsule gelatin is used.
 Gelatin also used as suppository base, as an emulsifying agent and
suspending agent.

26. Thermal analysis of the polymers is the
important phenomenon to study the stability
and degradation of polymers.
Method :-
a) TGA
b) DSC
c) Thermo mechanical analysis

27.  Definition :
Biodegradable polymers are defined as polymers
comprised of monomers linked to one another through
functional groups and have unstable links in the backbone.
 They slowly disappear from the site of administration in
response to a chemical reaction such as hydrolysis.
 Material progressively releasing dissolved or dispersed drug,
with ability of functioning for a temporary period and
subsequently degrade in the biological fluids under a controlled
mechanism, in to product easily eliminated in body metabolism
pathway.

28.  Biodegradable polymers can be classified in two:
1. Natural biodegradable polymer
examples:
a) Collagen
b) Albumin
c) Casein
d) gelatin
e) xanthum gum
f) gaur gum
g) chitosan
h) chtin
2. Synthetic biodegradable polymer
examples: Polyanhydrides, Poly(ß-Hydroxybutyric Acids) etc.
 Synthetic biodegradable polymer are preferred more than the natural biodegradable
polymer because they are free of immunogenicity & their physicochemical
properties are more predictable &reproducible

29.  Localized delivery of drug
 Sustained delivery of drug
 Stabilization of drug
 Decrease in dosing frequency
 Reduce side effects
 Improved patient compliance
 Controllable degradation rate

30. 12/24/14