All Details in a easy fashion on Pharmaceutical Polymers

1. POLYMER
SCIENCE
By Manjeet Singh Ramgadiya

2. History Of Polymers
Polymers are commonly referred to as “Plastics”
The first semi-synthetic polymer ever made was
Guncotton (cellulose nitrate)-by Christian F.Schonbein in
1845.
The manufacturing process for this polymer was
changed over the years due its poor solubility,
processability & explosivity resulting in a variety of
polymers such as celluloid(plasticized cellulose nitrate),
cellulose acetate & hydrolyzed cellulose acetate soluble
in acetone.

3. Contd…
In 1872, Bakelite, a strong &durable synthetic
polymer based on phenol & formaldehyde was
invented.
Other synthetic polymers were invented later
including Polyethylene-1933, Poly(vinyl
chloride)-1933, Polysterene-1933, Polyamide-
1933, Teflon-1938,& synthetic rubbers-1942.

4. Applications
They are used as wire insulation coating or as
insulating housings.
Conductive polymers are used as compact capacitors,
in antistatic coating, as electromagnetic shielding for
computers, transistors, light emitting diode, solar cells.
They are extensively used in automobile industry. The
major aim of the industry is to decrease the weight of
the automobile in order to reduce fuel consumption &
consequently emission of CO2.
Replacement of steel rods by polymeric fibers is very
effective to eliminate the problems of corrosion of
steel rods in concrete.
Footballs are made from polymethane.

5. PharmaceuticalApplication Of
Polymers
• Polymers are used in manufacturing of polyolefin
bottles, polystyrene vials, rubber closures, rubber
& plastic tubing for injection sets & flexible bags
of plasticized polyvinyl chloride to hold blood
&intravenous solutions.
• Unit –dose packaging make use of unplasticized
polyvinyl chloride for cups &trays
• Polyester film for strip-package or blister
package containers.

6. Contd..
• Water soluble polymers are used to coat tablets.
• Some polymers such as hydroxypropyl
methylcellulose(HPMC),& hydroxy
propylcellulose(HPC), NaCMC, are used as binders for
tableting granulation .
• Ethylcellulose(EC) being insoluble in water, is combined
with water soluble polymers to influence the dissolution
rate of the coating film.
• Synthetic &natural polymers are to thicken suspension
&ophthalmic solutions.

7. Contd..
• They are used to stabilize emulsion
&suspension.
• They are used to form water soluble jellies &
ointment bases.
• Polymers are employed in sustained release
dosage forms as shells for microencapsulated
drugs.
• Polymers used as coatings, binders, taste
maskers, protective agents, drug carriers
&release controlling agents.

8. DEFINITION: A polymer is a large molecule made up of
many repeating units.
 The word “polymer” means “many parts.”
 Monomers bond together to form polymers.
 A monomer is a small molecule that combines with
other molecules of the same or different types to form
a polymer.
 The structure of a polymer is displayed by showing the
“repeating unit”(monomer) or “mer” and an “n”
number that shows how many monomers are
participating in the reaction.
 If two, three, four, or five monomers are attached to
each other, the product is known as a dimer, trimer,
tetramer, or pentamer, resp.
POLYMERS IN GENERAL

10.  An oligomer contains from 30 to 100 monomeric
units.
 Product containing more than 200 monomers are
simply called a polymer.
 The polymer formed by the long chain of covalent
bonded single atom such as carbon or silicon alone
that forms the backbone of the polymer are called
homochain polymers. Example: -S--S- , -Si--Si-
 Heterochain polymers contain other atoms in the
backbone.
 Example: -C--S- , -C—O-

11. Homopolymers: They consist of a single monomer.
Ex:Many naturally occurring polymers like cellulose and
natural rubber are homopolymers.
COPOLYMERS : These incorporate two monomers in
their structure.
Ex:Proteins are co-polymers of amino acids.

12. TYPES OF CO-POLYMERS
RANDOM CO-POLYMERS: The monomers attach
randomly and follow no particular sequence, there will
be no preference for which monomer is added next.
ALTERNATE CO-POLYMERS: In such type of polymers the
two mers alternate.
BLOCK CO-POLYMERS: These contain long sequences of
same mer.

13. GRAFT CO-POLYMERS: In this type the monomers attach to an
already existing polymer.
Example: grafting of various monomers such as acrylic acid,
acrylamide, etc. onto the cellulose backbone of carboxymethyl
cellulose(CMC).

14. TYPES OF POLYMERS
LINEAR POLYMERS: These consist of long and straight chains.
Example: PVC.
BRANCHED POLYMERS: They contain linear chains having some
branches.
Example: low density polymer.
CROSS LINKED POLYMERS: They are formed from bi-functional
or tri-functional monomers and contain strong covalent bonds.
Example: bakelite, melamine.

15. THERMOPLASTIC POLYMERS : These are linear or slightly
branched long chain polymers, which can be softened on heating
and reversibly hardened on cooling repeatedly. Their hardness is
a temporary property and varies with temperature.
Example: polyvinyl chloride, polyethylene, nylon, acrylic.
THERMOSETTING POLYMERS : A cross-linked or network polymer
that is insoluble and infusible.
Example: bakelite.

16. POLYMERISATION
• THE PROCESS BY WHICH MONOMERS BOND IS CALLED
POLYMERISATION.
• THE NUMBER “n” OF REPEAT UNITS OR MERS PER
MACROMOLECULE IS CALLED DEGREE OF
POLYMERISATION(DP).
TYPES:
CONDENSATION POLYMERISATION: It is also called step-wise
polymerisation.
Two or more monomers carrying different reactive functional
groups interact with each other. There are no radicals
involved in this polymerisation.
Example: Nylon is prepared via condensation polymerisation
of diamine and diacid chloride.

17. ADDITION POLYMERSIATION: The polymer is formed from the
monomer, without the loss of any material, and the product is
the exact multiple of the original monomeric molecule.
This process involves three steps:
A. CHAIN INITIATION STEP: A Free-radical attacks the double
bond of a monomer. In this way, the radical is transferred to
the monomer and the monomer radical is produced.
B. CHAIN PROPOGATION STEP: The monomer radical is also able
to attack another monomer and then another monomer. Thus
a macroradical is formed.
C. CHAIN TERMINATING STEP: Macroradicals prepared may
undergo reaction with another macroradical, thus terminating
the chain.
Example: styrene shows free-radical polymerisation to form
polystyrene.

20. MOLECULAR WEIGHT OF POLYMERS
• POLYMERS ARE HIGH MOLECULAR WEIGHT COMPOUNDS.
1. WEIGHT AVERAGE MOLECULAR WEIGHT
𝑀𝑤 =
𝑁𝑖𝑀𝑖𝑊𝑖
𝑁𝑖𝑀𝑖
• Mw – Weight average molecular weight.
• Mi – Total molecular weight of monomer.
• Ni – Number of monomer molecules.
• Wi – Weight fraction of each molecule.
2. NUMBER AVERAGE MOLECULAR WEIGHT
𝑀𝑛 =
𝑁𝑖𝑀𝑖
𝑁𝑖

21. REFERENCES:
MARTIN’S PHYSICAL PHARMACY 4TH AND 6TH EDITION.
‘POLYMER SCIENCE’ BY GOVARIKAR.