1. Polymer science

2. DEFINITION
A Polymer is a substance composed of molecules with a large molecular mass of repeating structural units or monomers connected by covalent chemical bonds.

4. Types Of Linking In Polymers
Linear Polymers:
A polymer in which the molecules form long chains without branches or cross-linked structures.
examples: nylon, polyester, PVC etc.
Branched Polymer:
A polymer chain having branch points that connect three or more chain segments.
Examples: polythene, glycogen, starch etc
Cross linked Polymer:
Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds.
Examples: malamine formaldehyde resin etc
Linear & Branched Polymers are know as thermoplastic materials.
Cross linked Polymer are know as thermosetting materials. 4

5. Polymer classes include
Bio polymer
Conductive polymer
Co polymer
Fluoro polymer
In organic polymer
Poly ester
rubber
silicone
Synthetic rubber
Vinyl polymer

6. Classification of polymers
A. Depending on response to heat a. Thermoplastic : linear or slightly branched Solid melt solid resolidification Weak attractive forces hence, can be remolded. Eg :PE, PVP,PVC etc.

7. Classification of polymers
a.Depending on response to heat
b.Thermosetting: Extensive cross linking covalently
Solid Decomposed solid
Chains cannot be easily broken.
Eg : Epoxy resin, Poly urethane.

8. Classification of polymers (b)Based on chemical reaction
Condensation polymerisation
Addition polymerisation

9. Classification of polymers
Addition polymerization
Condensation polymerisation

10. Classification of polymers (C.) Based on repeating units
Homo polymer: [A-A-A-A]
Co polymer :
[A-B-A-B-A-B]
Alternating copolymers :
[A-B-A-A-B-A-B-B]
Random copolymers
[A-B-B-B-A-B-B-B]
Block copolymers:

11. Classification of polymers (D.)Based on origin of polymer
(i )Natural polymers
Eg:Gelatin, Xantum gum , Sodium alginate etc.
(ii.)Semi synthetic polymers
Eg: Methyl cellulose, HPC, HPMC, etc.
(iii.)Synthetic polymers
Eg ;carbopol, PVA, PVP, PEG,etc.

12. Classification of polymers (E). Based on degradation properties
Non bio degradable Eg:EC, PVC.
Bio degradable
Bulk eroding polymer eg:PLGA
Surface eroding polymers eg:Polyanhydrides

13. Classification of polymers
Natural and synthetic polymers
cotton., silk ,wool
PVC, nylon ethylene
Organic and inorganic polymers
Glass , silicone, rubber
Thermoplastic
Thermoplastic &
Poly ethylene, sealing wax.
Plastics,Elastomers, Fibers, Liquid Resins
PVC, polystyrene,PMC
Nylon terelene

14. Molecular weight
There are different ways that molecular weights of a polymer can be expressed:
By number of chains
By the weight of chains
By viscosity
The two most common ways are
Number(Mn)
And weight average calculations

15. Molecular weight determination
1. Number Average Molecular Weight
Molecular weight is determined by calculating the total molecular weight of monomer and total number of monomer.
Mi- total molecular weight of monomer.
Ni- number of monomer molecules.
Mn- number average molecular weight.

16. Molecular weight determination
2. Weight Average Molecular Weight
M - weight average molecular weight.
Mi- total molecular weight of monomer.
Ni- number of monomer molecules.

17. Characteristics of ideal polymer
Inert
Non toxic
Good mechanical strength
Easily administered

18. CRITERIA FOLLOWED IN POLYMER SELECTION
The polymer should be soluble and easy to synthesis
It should have finite molecular weight
It should be compatible with biological environment
It should be biodegradable
It should provide good drug polymer linkage

19. Preparation of polymer solution
Upon contact , the solvent molecules diffuses into the solid particles swell them and then into gel particles
The solvated polymer molecule diffuses out into the solvent . By stirring it reduces the thickness of the stagnant liquid layer surrounding each particle
Powders or grains are added to solvent. Stirring done inorder to prevent aggregation that forms lumps.
Eg: MC should be dispersed with high shear in about 1/4th the total amount of water heated to 80 Cto 90 c
If particles are wetted and dispersed the rest of water is added cold to about 50 c. Swells and dissolves the dispersed paticles fast with moderate shear.Eg:HPC,HPMC o o o

20. Conti………………. Eg:PVA &SCMC are soluble in hot than in cold water.
So dipersed in ice cold water followed by dissolution at 90oc
Eg: Dissolved in 80% toulene &20%ethyl alcohol . First toulene is added , the alcohol is then added to effect prompt dissolution.
Cellulose derivatives are stored for 48 hours after dissolution to promote full hydration , viscosity, & clarity.

21. Thermodynamics of polymer solutions
For the dissolution of a polymer in the solvent at a temperature T , the Gibbs free energy of mixing is
ΔG = ΔH - TΔS
The important points to be considered in thermodynamics of polymer solution are
Heat of mixing
Entropy of mixing
Free energy of mixing

22. Phase seperation
This technique is used in micro encapsulation of drugs by using high molecular weight long chain flexible polymers.
These polymers are used for their rate retarding properties
Phase seperation-coacervation
Core(drug)
Coat(polymer)
LMV(liquid manufacturing vehicle)

23. Cont……………… Rigidisation of micro capsules
To achieve this phase seperation different methods employed are
Changing in temperature
Addition of incompatible polymer
Non solvent addition
Salt addition
Polymer polymer interactions
How the deposition of coat over core materials occurs?
Rigidisation of micro capsules
Formed embryo microcapsules are gets hardened by various methods like
Thermal linking
Cross linking

24. Polymers in solid state
Solid polymers depends on:
Mechanical ,
permeability,
electric,
thermal,
optical properties.
These factors determine the flexibility and strength of the polymers
For amorphous polymers cross linking or the fillers may be desirable.

25. Properties of polymers
A.Physical properties of polymers
The properties of polymer depends on many factors including
inter and intrachain bonding
Presence of additives
Chain size and geometry
Molecular weght distribution
Polymers do not boil

26. a.Physical properties Glass transition temperature(Tg) (Tg)
Vinyl polymers
(Tg)Below room temperature
flexible
Rubber &plastic
Glass transition temperature(Tg) (Tg)
Condensation polymers
(Tg) above room temperature
Hard plastics
Many polymers brittle at room temperature.
To become liable plasticizers added that allow segmental mobility
Eg:
PVC, & poly styrene

27. a. Physical properties conti…………
Inflexible region Hard
Flexible region Soft
Urethane portion Hydrogen bonding Hard
Polyether portion Flexible Soft
Poly urethanes
Room temperature

28. b.Chemical properties
Different side groups on the polymer can lend to:
Ionic bonding
Hydrogen bonding
Polymers containing amide or carbonyl groups can form hydrogen bonds between adjacent chains.
Polyesters have dipole –dipole bonding between the oxygen atoms in C=Ogroups and the hydrogen ato.ms in C-H groups.
Dipole bonding is not as strong as hydrogen bonding

29. c. Mechanical properties
Depending on their structure , molecular weight , and intermolecular forces, polymers resist differently when they are stressed.
For elastic materials the stress and strain correlation is linear upto the failure point
For fibres and highlt cross linked polymers the slope of the stress and strain line is steeper.
Energy is needed to break the polymer . The area under the stress/strain measures it.
The larger the area, is the tougher the polymer.

30. Tacticity
Tacticity describes the relative steriochemistry of chiral centers in neighbouring structural units within a macromolecule. There are three types :
Iso tactic
A tactic
Syndiotactic

31. Thermal characterisation
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

32. THERMOGRAVIMETRICAL ANALYSIS (TGA)
This method provides indication for thermal stability and upper limit of thermal degradation where loss of sample begins.
This method only measures loss of volatile content from the polymer.
This method has limitation that it can not detect temperature at chain cleavage of chain takes place.

33. Differential Scanning Calorimetry (DSC)
parameters measured-
Glass transition temperature (Tg)
Crystalline melting point
Heat of fusion
Heat of crystallization
It requires placing of Reference and test sample for the continuous monitoring in the heating chamber.

34. Differential scanning calorimetry

35. Thermo Mechanical Analysis (TMA)
This method is used for determination of deformation of polymer sample as a function of temperature placed on platform in contact with probe.
It measures transition from glassy to a rubbery polymer and gives idea about softening temperature.

36. Pharmaceutical applications of polymers
1.Biomaterials for delivery systems
Polyurethanes
Polysiloxanes
Poly methyl methacrylate
Poly vinyl alcohol
Polyethylene
Poly vinyl pyrrolidone

37. Biomaterials for delivery systems
Currently being used polymers
Polymers which degrade in body
poly (2-hydroxy ethyl methacrylate).
Poly( acrylic acid)
Poly(N-vinyl pyrrolidone)
Poly(methyl methcrylate)
Poly vinyl alcohol
Poly acryl amide
Poly(methacrylic acid).
PEG
Polyethylene-co-vinyl acetate
Poly actides
Polyglycolides
Poly (lactide-co-glycolides)
Poly anhydrides
Poly orthoesters

38. Polymers in controlled drug delivery
Micrograph of particles used to carry drugs to the lung
Drug levels in the blood with
Traditional drug dosing
Controlled delivery dosing

39. Controlled release mechanisms
Drug delivery from a typical matrix drug delivery system
Drug delivery from typical reservoir devices:
Implantable or oral systems
Trans dermal systems

40. Bio degradable systems
Drug delivery from :
Bulk eroding and
Surface eroding bio degradable systems
Bio degradabl micro particles of
60:40 lactide :glycolide PLGA
Bio degradable micro particle of 75:25
lactide:glycolide PLGA after 133 days
of degradation in water

41. Applications of polymers
Dental
Ophthalmic
orthopedic
Sutures
Drug delivery
Drugs
Tablets
Liquids
For controlling the flow semi solids

42. References
Bio pharmaceutics and pharmacokinetics by: D.M.Bharmankar, Sunil.B. Jaiswal.
Govariker V. R., Viswanathan N. V., Sreedhar J., “Polymer Science”, New age publications,
Jain N.K., Controlled and novel drug delivery, CBS Publisher,New delhi,
Martin A., Swarbrick J., Commarata A., Physical pharmacy, K.M.varghese company, Bombay,
Sinko P.J.,Physical pharmacy and pharmaceutical sciences, fifth edition, lippincot williams & wikins co.,

43. THANK YOU