1. Classification of Polymers
(Molecular Structure of the polymers)
1. Thermoplastics:
heating
(linear or branched polymers)
cooling
Melt
Melt
Not crystallize Amorphous (amorphous region)
Crystallize Semi-crystalline (crystalline and amorphous region)
Melting temperature (Tm)
Glass transition temperature (Tg)
Glassy state  Ruberry state

2.   2. Elastomers: 3. Thermosets:
Crosslinked Rubbery Polymers (low crosslink density)
 High extension (e.g. 3x to 10x)
stress
 Intractable 
3. Thermosets:
heating
Networks Polymers (high crosslink density)
 Rigid Material
stress 
heating

3. Degree of polymerization (DP, x)
The number of repeat unit in the polymer chain
R-C- H
-C-
- C-R
DP= 8
The product of DP & molecular weight of a repeat unit is the molecular weight of a polymer chain
molecular weight of a chain = molecular weight of repeat unit X DP
-C- H Cl n

4. Skeletal Structure
Branch point or junction point
linear chain polymer (two ends)
branched chain polymer
Network (crosslinked) polymer
Degree of crosslinking or crosslinked: no of junction points per unit volume
No melting on heating
Nonsoluble in any solvent
Major differences in properties:
the melting point of linear polyethylene is about 20 C higher than branched chains

5. Statistical Copolymer
Homopolymer
Polymers whose structure ca be represented by a multiple repetition of a single unit which may contain one or more species of monomer unit (structural unit)
── A── n
-A-A-A-A-A-A-A- A A A A A A A A A A A A A A
Copolymer
Polymers whose molecules contain two or more different types of repeat unit
-A-B-A-B-A-A-B- A B A B A A B A B A B A A B
Statistical Copolymer
Sequential distribution of repeat units obeys the known statistical laws
Random Copolymer
distribution of repeat units is truly random
-A-B-A-B-A-A-B-A-B-B-B-A-A-B-A-A-A-B-B-A-B-

6. Alternating Copolymer:
Distribution of two types of repeat unit alternately along the polymer chain
-A-B-A-B-A-B-A-B-A-B-A-B-A-B-A-B-
The properties of statistical, random and alternating coploymer are generally intermediate to those of corresponding homopolymer
Bock Copolymer:
Linear copolymer in which repeat units exist only in long sequences (blocks) of the same types
-A-A-A-A-A-A-A-A-B-B-B-B-B-B-B-
AB di-block copolymer
-A-A-A-A-A-B-B-B-B-B-A-A-A-A-A-
ABA tri-block copolymer
Graft Copolymer:
Branched polymers in which the branches have a different chemical structure to that of the main chain
Properties: characteristics of each of the constituent homopolymer
Unique
B-B-B-B-B-B-B-B-B
-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-
B-B-B-B-B-B-B-B-B

7. Synthetic Biopolymers
Importance of composition, mol. Wt, amount of unreacted polymer, catalyst involved, degree of crystallinity, additives on biocompatibility, mechanical and other properties

8. List of the more important Polymers in Biomedical Applications
PE & PP
UHMWPE (2 x 106 g/mol)
Isotactic, syndiotactic, atactic forms
Acetabular cups, knee joints, blood vessels, suture
Perfluorinated Polymers
PTFE: fixation of heart valves, impregnated into PET sutures, hearing aids
Acrylic Polymers
PMMA: opthalmology, bone cement
Additives such as barium sulfate or barium oxide important
Composition of moldable dough determines short curing time and other properties
Hydrogels: intraocular lenses, cartilage material

9. List of the more important Polymers in Biomedical Applications
Polyurethanes:
urethane linkage: (-O-CO-NH-)
Segmented polymers: soft and hard segments
Aorta patch grafts, Blood tubings
very good hydrolytic stability
Polyamides
Nylon
Good fiber forming properties due to interchain hydrogen bonding of intracardiac catheters
Number and distribution of amide bonds determine properties such as Tg etc
Silicone rubber
Alternate atoms of silicon & oxygen in main chain with organic side groups attached to silicon – propers varied by careful compounding
Catheters where PE, teflon more irratating to tissues, maxillofacial surgery, nasal supports, Cosmetic surgeries, aesthetic surgeries.

10. A little on Manufacturing and Secondary operations for biomaterials
Castings, Forging & HTs
Liquids are normally poured into moulds to be cast to be cast into ingots for fabrication of medical devices
The cast products are then processed in a number of ways depending on the desirable mechanical properties.
These include:
Drawing, Pressing, Forging, machining, Precipitation hardening, Tempering and other HTs
Other Processes include those through:
Powder Metallurgy
Sol gel
CIP, HIP, SPS, reaction bonding etc

11. SPS
Spark plasma sintering a novel technique used to sinter ceramics, metals and composites within a few minutes and to obtain densities greater than 99.9%

12. Surface Improvements These include mostly: Anodization Flame Spraying
Surface alloying/Electroplating
PVD & Ion Plating
Grinding/Polishing/Sand Blasting
Plasma Polymerization

13. Classification of Polymerization Reactions
Monomer: A species must be capable of being linked to two (or more) other species by chemical reaction (Functionality of two or higher)
Condensation (step reaction) polymerization: Step polymerization
In the polymer, there are fewer atoms in repeat units than monomers (Carothers, comparison of formula of monomer and repeating unit)
reaction of many monomers into a polymer chain with elimination of small by products molecules
It involves the condensation reaction between two polyfunctional molecules to produce one larger molecule. (polymerization mechanism)
Monomer is rapidly consumed in early stages +  +  +  + 
Step-growth polymerization + 

14. Linear Step polymerization
reactions of difunctional monomers
It involves successive reactions between pairs of mutually–reactive functional group
monomers
Species with mutually-reactive functional groups
Functionality: the number of functional groups present on the molecule
polymers O O
Easter linkage
OH-CH2-CH2-OH+ HOC— —COH
Ethylene glycol
Terephthalic acid O O
HOC— —COCH2-CH2-OH + H2O
Nonlinear Polymers:
reactions of monomers of functionality greater than two
Trifunctional monomers
branched polymer
Network polymers
Terephthalic acid + glycerol (OH-CH2-CH(OH)CH2-OH
nonlinear polymer

15. 2. Addition (chain reaction) polymerization : chain polymerization
In the polymer, there is identical formula of repeat units and monomers (Carothers)
addition of many monomers into a polymer chain without elimination of small by products molecules.
It involves the chain reactions, in which the chain carrier may be a free radical (any substance with an unpaired electron), an ion (cation or anion), reaction of monomer with reactive end group
Monomer is being consumed steadily throughout reaction
Chain-growth polymerization
R-C- H
-C-
- C-R

16. Free-Radical Polymerization X = -H, ─ , -F, -COOCH3,-Cl, -OCOCH3
Chain Polymerization
Free-Radical Polymerization 1
Initiation
Propagation
Termination
Free-Radical: An independently-existing specie, which possess an unpaired electron, normally highly reactive & short lifetime
Free-Radical Polymerization
The chain polymerizations in which each polymer molecule grows by addition of monomer to a terminal free-radical reactive site (active center) + + + +
Active center is transferred to newly-created chain end upon addition of new monomer
CH2=CHX vinyl polymer
CH2=CR1R2
X = -H, ─ , -F, -COOCH3,-Cl, -OCOCH3

17. The main polymer Manufacturing Techniques
Bulk
Melt
Solution
Suspension
Interfacial
Emulsion

18. Lens Abberrations

19. Biomaterials Case Study
Q.1) Conduct a case study on one Biomedical Device/Implant. Your study should include
Name and function of the implant
A proper study for selection of materials for that implant
State the material you have finally selected and give your reasoning:
Include details/important properties of the material
Effectiveness in the application you have chosen
Any Advantages or Drawbacks of the material
Production methods
Mention the name of any company if it is currently being manufactured in industry

20. Nanomaterials Assignment
Q) Explain the following and their application through nanotechnology. You must include information about the materials involved and how they are being used for their particular applications.
Nano/biosensors Drug delivery
Quantum dots Endofullerenes
Interconnect materials Nanobots
Diamondoid Structures
Hydrogen Storage & Clean Energy