Its all about polymers its classification, method of preparation, properties and applications.

1. Polymers
Presented by
Ms. Aboli Malokar
M. Pharm (pharmaceutics) 1st sem
Dadasaheb balpande college of pharmacy

2. CONTENTS
 INTRODUCTION
 CLASSIFICATION
 METHOD OF PREPARATION
 PROPERTIES
 APPLICATIONS
 REFERENCES

3. DEFINATION
Polymers also known as macromolecules, are very large molecules
consisting of many repeating units called monomers (smaller
molecules) and are formed by a process called polymerization.

4. HISTORY
 In 1845, the first semisynthetic polymer ever made was
guncotton(cellulose nitrate) by Christian F. Schonbein.
 In 1872, Backelite a strong and durable synthetic polymer based on
phenol and formaldehyde was invented.
 In 1933, polyethylene, 1935 polyamide, 1938 Teflon, 1942
synthetic rubber were invented.

5. INTRODUCTION
 Polymers are very large molecules made when hundreds of
monomers join together to form long chain.
 The word ‘polymer’ comes from the Greek words poly means
‘many’ and mer means ‘parts’.
 The monomers can be linked together in various ways to give rise
to various types of polymers are linear polymer, branched polymer
and three dimensional crosslinked polymer.

6. a) linear polymer b) branched polymer c) crosslinked or network polymer

7. • A polymer is a macromolecule composed of either
 Many repeating units of one type (same monomer)
i.e. homopolymer.
 Many repeating units of several types (different monomers) i.e. copolymer.
-A-A-A-A-A-A-A-A-A-A- Homopolymer
-A-B-A-B-A-B-A-B-A-B- Copolymer
A - B – B – A – B – A – A Random copolymer
A – B – A – B – A – B – A Alternating copolymer
A – A – A – B – B – B Block copolymer

8. IDEAL CHARACTERISTICS
 Should be inert
 Should be compatible with environment
 Should be non toxic
 Easy and inexpensive to fabricate dosage form
 should be biodegradable and biocompatible
 It should provide good drug polymer linkage
 It should be versatile and posses a wide range of mechanical,
physical and chemical property.

9. Classification of Polymers
Based on
source
 Natural
 Synthetic
Based on
Chemical
nature
 Organic
 Inorganic
Based on Thermal
behavior
 Thermoplastic
 Thermosetting
Based on their
ultimate forms
 Plastics
 Elastomers
 Fibres
 Liquid
resins

10. Based on source
Natural Polymers :- Polymers which are isolated from natural materials are called
as natural polymers.
E.g. :- Cotton, silk, wool, rubber
Cellophane, cellulose rayon, leather are chemical modifications of natural
polymers.
The Cellulose is another natural polymer which is a main structural component of
the plants.
Cotton Rubber
Wool
Silk

11. Synthetic Polymers :- polymers which are synthesized from low molecular weight
compounds are called synthetic polymer.
E.g. :- Polyethylene, PVC, nylon, terylene
Polyethylene Terylene
Nylon
PVC

12. Based on Chemical Nature
Organic Polymers :-Polymers whose backbone chain essentially made of carbon
atoms is termed an organic polymers.
Organic polymers are derived either from petroleum or from plants, animals,
microorganisms. Hence, they are generally accessible in large quantities and at
nominal cost.
The majority of synthetic polymers are organic.
E.g. :- Cellulose, Proteins
 Inorganic Polymers :- The molecules of inorganic polymers contain no carbon
atom in their chain backbone.
E.g. :- Glass, Silicone, Rubber

13. Based on Thermal Behaviour
Thermoplastic Polymers :- Polymers that soften on heating and stiffen on
cooling are termed as thermoplastic polymers.
The process of heating, reshaping and retaining on cooling can be repeated
several times.
When frozen, thermoplastics becomes glass like and subject to fracture.
Popular uses of thermoplastic polymers include the manufacture of pipes,
ropes, belts.
E.g. :- polyethylene, PVC, nylon, sealing wax

14. Thermosetting polymers :- These polymers undergo some chemical change on
heating and convert themselves into an infusible and insoluble mass.
Once set, cannot be reshaped
E.g. :- Backelite, epoxy resin, polyesters

15. Based on their ultimate forms
Plastics :- A polymer is shaped into hard and tough utility articles by the application
of heat and pressure is used as plastic.
E.g. :- polystyrene, PVC, Polymethyl methacrylate
Elastomers :- When vulcanized into rubbery products exhibiting good strength and
elongation, polymer are used as elastomers.
E.g. :- Natural rubber, synthetic rubber, silicon rubber.
Fibers :- When drawn into long filament-like materials, whose length is at least 100
times its diameter, are called as fibers.
E.g. :- Nylon, terylene

16. Liquid resins :- Polymers used as adhesives, plotting compounds, sealants in
liquid form are described as liquid resins
E.g. :- Epoxy adhesives, polysulphide sealants

17. Biodegradable polymers Non-biodegradable polymers
• They are degraded in the body to the
simple molecules like water and co2
which are easily eliminated in the urine
• Mainly used for parentral drug delivery
system and can also be used for oral
drug delivery system
• Examples :- Natural polymers like
gelatin, collagen and synthetic
polymers like polycaprolactone and
polyethylene glycol.
• They are not degraded in the body
• Only for oral administration, they
cannot be used for parentral drug
delivery of drugs
• Examples :- Semi synthetic polymers
like ethyl cellulose.

18. Method of preparation of polymers
Bulk polymerization
This polymerization carried out by adding a soluble initiator to pure monomer.
The mixture is constantly agitated and heated to polymerization temperature.
Once the reaction starts, heating is stopped as the reaction is exothermic.
The heat generated is dissipated by circulating water jacket.
Viscosity increases dramatically during conversion.
The method is used for the polymerization of liquid state monomers.
It is usually adopted to produce free radical polymerization of methyl
methacrylate or styrene and also for vinyl chloride to get PVC resin.

20. Solution Polymerization
This polymerization carried out by taking monomer along with initiator
dissolved in solvent.
The mixture is kept at polymerization temperature and constantly agitated.
After the reaction is over, the polymer is used as such in the form of polymer
solution or the polymer is isolated by evaporating the solvents.
Polymer so formed can be used for surface coating.
It is used for the production of polyacrylonitrile, block copolymers are also
made exclusively by this technique.

22. Suspension Polymerization
In this process monomer is dispersed in a dispersing medium.
Initiators used are monomer soluble E.g. dibenzoyl peroxide.
The dispersion is maintained by continuous agitation and the droplets are
prevented to coalesce by adding suitable water soluble protective colloids, surface
active agents and by stirring.
 polymerization occurs in the monomer droplets suspended in the dispersing
medium and product formed being insoluble in water.

23. The product is separated out in the form of spherical pearls or beads of polymer.
They can be used directly for some application or can be extruded and chopped to
form large easily moulded pallets.
This technique is used to form expandable polystyrene beads, styrene-divinyl
benzene copolymer beads and polyvinyl acetate beads.

25. Emulsion polymerization
This technique is used for the production of large number of platics and elastomers.
The system consists of water soluble monomer, dispersion medium and emulsifying
agents or surfactants.
The monomer is dispersed in the aqueous phase, not as discrete droplets, but as a
uniform emulsion.
The size of monomer droplet is around 0.5 to10µm in diameter depending upon the
polymerization temperature and rate of agitation.
The emulsion of monomer in water is stabilized by a surfactant.
A surfactant has a hydrophilic and hydrophobic end in its structure.
When it is put into a water, the surfactant molecules gather together into aggregates
called micelles.

26. The hydrocarbon tails (hydrophobic) orient inwards and head (hydrophilic)
orient outwards into water.
The monomer molecules diffuse from monomer droplets to water and from water
to the hydrocarbon center of micelles
This technique is used to produce polybutadiene, polychloroprene, polystyrene,
acrylonitrile-butadiene-styrene terpolymer(ABS)

27. Polymer properties
Molecular weight :- molecules within a given polymer mass will have
different molecular weight. So that molecular weight of polymer are described
in terms of average molecular weight.
Polymer molecular weights can be defined in different ways, most common
molecular weights are the number average molecular weight, Mn, the weight
average molecular weight, Mw, and the viscosity average molecular weight,
Mv.

28. The ratio of Mw/Mn also known as the polydispersity index
It indicated broadness of molecular weight distribution, and for Mw/Mn = 1
the polymer is monodispersed i.e. all polymer molecules within a polymer
mass have the same molecular weight.

29. Polymer hydrophobicity
When a polymer is placed in an aqueous environment it will gradually
absorb water, and the amount of absorb water is determined by the polymer
structure.
According to nature of polymer-water interaction, polymers can be
classified into
Hydrophobic polymer
Hydrophilic polymer
Water soluble polymer
hydrogels

30. Glass transition temperature
When a crystal melts, the polymer volume increases significantly as the solid
turns to a liquid. The melting temperature(Tm) represents the first order
thermal transition in polymers.
The volume of an amorphous polymer gradually changes over a wide
temperature range or so called glass transition temperature(Tg). This behavior
represents a second order thermal transition in polymers.
At temperatures well below the (Tg) amorphous polymers are hard, stiff, and
glassy.
At temperature well above the Tg polymers are in the form of liquid or
becomes rubbery.

32. Crystallinity
Crystallinity is indication of amount of crystalline region in polymer with respect
to amorphous content.
With increased temperature, the crystal cells starts to melt and the whole polymer
mass suddenly melts at a certain temperature
Amorphous structure is formed due to either rapid cooling of a polymer melt in
which crystallization is prevented.
Polymer strength and stiffness increase with crystallinity.
Crystallinity increases the barrier properties of a polymer packaging.

33. Pharmaceutical Applications
Conventional dosage form
Binder
E.g. polyethylene, polyolefin
Controlled release dosage form
Transdermal patch
E.g. polyethylene glycol
 Contraceptives
 E.g. medroxyprogesterone acetate- vaginal contraceptive ring
 It consists of a drug reservoir and polymer coating material. Through this layer
the drug releases slowly.

34.  Drug delivery and the treatment of diabetes
 Here the polymer will act as barrier between blood stream and insulin.
 E.g. polyacrylamide or N,N-dimethylaminoethylmethacrylate
 Application of polymers in solid dosage forms
• In Tablets
 Methyl cellulose, hydroxyl ethyl cellulose, hydroxyl ethyl methyl cellulose used
as binders
 Cellulose derivatives used as coating materials
 CAP, hydroxyl propyl methyl cellulose phthalate, polyvinyl acetate phthalate
are used as enteric coating material
• In capsule
 Gelatin a natural polymer which is the major ingredient in the manufacturing of
capsules

35.  Application of polymer in liquid dosage forms
• In suspension
 Acacia, tragacanth, cellulose derivative, xanthum gum are used as suspending
agents
 They enhances dispersion of solids in liquids
• In emulsion
 Tragacanth, tweens are used as emulsifying agents
 Polymers can be used as film coating in tablets
 Hyaluronic acid is used in controlled release ophthalmic preperations
 Natural gums are used as thickening agents e.g. polyethylene glycol
 Some polymers are used as suppository bases e.g polyethylene glycol

36. References
Gowariker V. R., Vishwanathan N. V., Sreedhar J., Polymer science, second
edition, new age international publishers page no 6-14
Robinson J. R., Lee V. H. L, Controlled drug delivery systems, fundamentals
and application, second edition, revised and expanded, page no. 152-155.