Self Introduction

B.S. (2006) and M.S. (2008)

Dept. of Chemistry, University of Dhaka
PhD (2011) in Polymer & Material Science
Postdoctoral Fellow (Dec 2011 –July 2013)
Faculty of Science, Hokkaido University, Japan
JSPS Postdoctoral Fellow (Oct 2015 –Dec. 2017)
Faculty of Science, Hokkaido University, Japan
Course No- Chem 143
Course Title – Chemistry of Materials Credit Hours: 2
Course Content
Glass: Classification, manufacture and application. Corrosion,
Paints. Varnishes and metallic coating: Composition and
applications of paints, varnishes and metallic coatings, methods
used in applying coating on metal surface. Polymer:
Polymerization, classification, mechanism of polymerization
and processing of polymer. Plastic: Fundamental
characteristics, classification, raw materials and
manufacture of plastics, some typical examples of plastics
and their uses. Fibers: Types of fibers, synthesis and
application of synthetic fibers. Rubber: Source of natural
rubber, chemical treatment of latex, synthesis and
properties of synthetic rubber. Lubricants: Chemistry of
lubricants, sources, properties, refining, chemical treatment and
industrial importance of lubricants.
Course No- Chem 143
Course Title – Chemistry of Materials Credit Hours: 2
Teacher # 2

Polymer: Polymerization, classification, mechanism of

polymerization and processing of polymer.
Plastic: Fundamental characteristics, classification,
raw materials and manufacture of plastics, some
typical examples of plastics and their uses.
Fibers: Types of fibers, synthesis and application of
synthetic fibers.
Rubber: Source of natural rubber, chemical treatment
of latex, synthesis and properties of synthetic rubber.
 Lecture Plan: Teacher-2
Lecture Topics
L1 General introduction
L2 Polymer: Classification and polymerizations
L3 Polymer: Mechanism of polymerization
L4 Polymer: Processing of polymer.
L5 Plastics: Fundamental characteristics, classifications
L6 Plastics: Raw materials and manufacture of plastics
L7 Plastics: Some typical examples of plastics and uses.
L8 Class Test-1
L9 Fibers: Types of fibers, raw materials, applications
L10 Fibers: manufacturing processes of synthetic fibres.
L11 Rubber: Sources of natural rubber
L12 Rubber: chemical treatment of latex
Rubber: synthetic reactions and properties of synthetic
L13
rubber.
L14 Class Test- 2
 Textbooks
Textbook-1 Materials Science and Engineering: An
Introduction

William D. Callister Jr., David G.

Rethwisch
Textbook-2 Textbook of Polymer Science, 3rd
Edition

Fred W. Billmeyer
Textbook-3 Industrial Chemistry, B. K. Sharma
Text book -4 Industrial chemistry, Shreve and Brink
Text book -5 Polymer Science and Technology, 1st
Edition, by Robert O. Ebewele
Course Outline
Course Outline
Course Outline
Course Outline
Course Outline
Course Outline
Chemistry of Materials
 Chemistry of Materials

MATERIAL
Physically exist, such as wood, stone, or plastic, having
qualities that is relating to, derived from, or consisting of matter
and that allow it to be used to make other things.

CHEMISTRY OF MATERIAL
Materials chemistry is the understanding, synthesis, processing,
and exploitation of compounds or substances in their
assembled form for various practical applications.
 Materials chemistry is a new and highly interdisciplinary
science that involves the use of chemistry for the creation,
characterization, and application of materials with interesting
or potentially useful physical or chemical characteristics.
 Substances of interest include inorganic, organic, polymeric,
and hybrid materials, and thus materials chemistry
incorporates solid-state chemistry, nanoscience, and polymer
chemistry.
 Materials chemistry is central to the development of new
technology and the global economy. As we look back,
synthetic materials have played a vital role in improving the
standard of living and the quality of human life worldwide.
 Essential for solving the greatest challenges of our time, from
sustainable energy storage and environmental challenges to
the development of quantum devices and quantum
communication technology.
 L2 Polymer: Classification and polymerizations

Outline
 Discovery of Polymer
 What is a Polymer?
 General formation of polymer
 Differences between polymer and macromolecule
 Classification of polymer
 Shape of polymer molecule
 Polymer Properties based on Degree of Polymerization
 Molecular weight of polymer

Book:
R. Ebewele, Chapter 1;
Chanda Page 18-29
Callister Page, Chap 14. 480-510
 Materials/Polymer

Why Polymer???
Development of civilization
Stone age → Bronze age → Iron age → Polymer age

Application of polymer
(Rubber, plastic, fibers, elastomers, coatings, adhesives,
protein, cellulose, synthetic leather)
Polymers around us
 Discovery of Polymer
Year of Polymer Products
discover
1868 Cellulose nitrate Eyeglass frame
1909 Phenol– Plastic,
formaldehyde Telephone handset, knob
1927 Cellulose acetate Toothbrushes, packaging
1927 Poly(vinyl chloride) Raincoats, flooring, Piping
1938 Polystyrene Kitchenwares, toys
1938 Nylon (polyamide) Gears, fibers, film, ropes
1943 Silicone Rubber good
1942 Polyester Boat hull, clothing
1971 Hydroxy acrylates Contact lenses
1973 Polybutylene Piping
1980… Polymer blend/hybrid
Ref. Historical_development_of_polymers; Rehan Ashraf, 2000, CRC press LLC
 What is a Polymer?
A human chain can be a Polymer???
Repeating unit: Human Link: Hand-to-Hand
 What is a Polymer?
Necklace of pearls can be a Polymer???

Necklace of pearls

Pearl: Monomer; Yarn: Covalent bond; Necklace: Polymer

Poly mer
many part (repeated part)

A long/large molecule consists a large number of

repeated small molecules and covalently bonded.
The repeating unit of the polymer is called
monomers.
Polymers are synthesized from a small molecule
by a process called polymerization
Criteria of a polymer
 High molecular weight
 Composed of many monomer units
n(CH2=CH2) (CH2-CH2)n,
n= No of repeating units or monomer
 The monomer units are joined together by covalent bond.

Is (NaCl)n crystal and (H2O)n ice is polymer?

United together by
(NaCl)n ionic bond
United together by
(H2O)n Hydrogen bonding
 Polymer formation

Solution Linear Branching Cross-linking

Networking
 Random/3D network structure of polymer
 Possesses high polymer concentration
 Have dimensional stability
 Polymer network: Dispersion medium; Water: Dispersed phase
 Example: Polyethylene
Monomer: Ethylene
Polymerization: Chemical reaction for
covalent bond formation
Polymer: Polyethylene

H2C CH2

CH2 CH2 CH2 CH2 CH2 CH2 CH2

 Polymerization to form Polyethylene
H2C CH2 H2C CH2

H2C CH2 H 2C CH2

H2C CH2

H2C CH2 H2C CH2 H2C CH2

CH2

H2C CH2 H2C CH2 H2C

 Structure of Polyethylene/polymer

Polyethylene is a long-chain hydrocarbon

26
What are the differences between macromolecules (Carotene, vitamin C etc.)
and polymer?

Composed by same
Polymer
repeating unit (monomers)
Composed by any repeating
Macromolecules
unit
 Polymer vs. Macromolecule

Hemoglobin Triglyceride
Polymer vs. Macromolecule
 Classification of polymer
1. Based on origin:
a) Natural: Natural Rubber
b) Synthetic: Fibers, elastomers, plastics, adhesives, PP, PVC
c) Semi-synthetic: cellulose acetate is a thermoplastic
polymer
2. Based on structure:
a) Homopolymer or Copolymer
b) Linear, Branched, Cross-linked, Network
c) Tacticity/stereo structure
d) Amorphous or Crystalline or semi-crystalline
3. Based on polymerization mechanism/formation
Addition, Condensation
4. Based on thermal behavior
Thermosetting, thermoplastic
5. Application and physical properties
Rubbers, Fibers, elastomers, plastics,

6. Number/type of monomer units

 Oligomer : few monomers, dimer, trimer, tetramer, pentamer, etc
 Telechelic polymer : polymer containing reactive end group that is capable of
entering into further polymerization or other reactions through its reactive end-
groups
 Telechelic oligomer : oligomer containing reactive end group
 Macromer (=macro monomer) : monomer containing long chain
 2. Classification based on structure
a) Homo-polymer or Copolymer
Homo-polymer : -A-A-A-A-A-A-A-A-
Co-polymer : -A-B-A-B-A-B-A-B-
Random copolymer : -A-B-B-A-B-A-A-B-

Alternating copolymer : -A-B-A-B-A-B-A-B-

Block copolymer : -A-A-A-A-B-B-B-B-A-A-A-A-B-B-B-B-

Graft copolymer:
 Types of copolymer

Random copolymer : -A-B-B-A-B-A-A-B-

Alternating copolymer : -A-B-A-B-A-B-A-B-

Block copolymer : -A-A-A-A-B-B-B-B-

Graft copolymer : -A-A-A-A-A-A-A-A-

 2. Classification based on structure
b) Linear, Branched, Cross-linked, Network (homo-polymer)
Linear

Branched

Cross-linked
 2. Classification based on structure
b) Linear, Branched, Cross-linked, Network

Linear Branched

Cross-linked Network
 Nature of polymer in terms of linearity
 Linear polymer are mostly soluble and fusible.
 Low branched polymer less resistant to solvents, chemicals
and heat.
 Highly branched polymer make the polymer relatively stiff.
 Highly branched polymer can make physical entanglement
or physical crosslinking or chemical crosslinking.
Restraining the molecular mobility, flexibility, or chain
fixing, and improving dimension stability. Therefore the
polymer become insoluble and infusible.
 The mechanical strength increase substantially due to long
branch crosslinking between polymer chains.

(Book: Ghosh page 11)

 Cross-linked polymer
A cross-link is a bond that links one polymer chain to another. They can be covalent or ionic
bonds.
 Nature of polymer in terms of crosslinking density

 Low cross-linked polymer are soluble, fusible, and they

have no three dimensional stability, and they are
mechanically very weak.
 Low cross-linked polymer are sometime less resistant to
solvents, chemicals and heat.
 Highly cross-linked polymer restrains the molecular
mobility, flexibility by chain fixing and improving
dimension stability. Therefore the polymer become
insoluble and infusible.
 The mechanical strength increase substantially due to
crosslinking between polymer chain.
 Types of crosslinking
Chemical crosslinking
Formation of chemical crosslinking
 Crosslinking by chemical reaction during polymerization
by using poly-functional instead of di-functional
monomers
 Crosslinking is a separate chemical reaction after the
formation of linear or branched polymer.
 Chemical crosslinking is formed either by covalent bond
or ionic bond.
Effect on polymer property on chemical cross-linking
 The polymer become insoluble, loses chain flexibility,
mechanically strong, controlled swelling.
Disadvantages of chemical cross-linking
 Once formed, cannot be dissolved, recycled.
 Stable against heating and cooling

Physical crosslinking
 Formed by some secondary valence forces, such as
physical interaction, H-bond, Vander-Waals forces,
hydrophobic interaction etc..
2. Classification based on structure
c) Tacticity/stereo structure

Tacticity – stereoregularity of chain

H H H H H H H H
isotactic – all R groups on
C C C C C C C C
same side of chain
H R H R H R H R

H H H R H H H R
syndiotactic – R groups
C C C C C C C C
alternate sides
H R H H H R H H

H H H H H R H H
atactic – R groups random C C C C C C C C
H R H R H H H R
2. Classification based on structure
c) Crystallinity

A. Amorphous
B. Crystalline or semi-crystalline

Amorphous Crystalline
Polymer chains randomly Chains are folded and packed
coiled and entangled in a regular manner with 3D
long-range order.
3. Classification based on thermal property
Thermoplastic vs Thermoset
Thermoplastics: Change shape/structure/reform upon heating

• No cross-links between chains.

• Weak attractive forces between chains broken by warming.
• Change shape - can be remoulded.
• Weak forces reform in new shape when cool down.
• Example: Polyethylene, polypropylene, polyvinyl chloride,
polystyrene, polybenzimidazole, acrylic, nylon and Teflon
3. Classification based on thermal property
Thermosets: Stable, keep shape, upon heating

• Extensive cross-linking formed by covalent bonds.

• Bonds prevent chains moving relative to each other.
• Cant be soften after heating and reshaped.
• Cant be remoulded.
• What will the properties of this type of plastic be like?
• Example: Epoxy resin, melamine formaldehyde, polyester resin and urea
formaldehyde
 Polymers – Molecular Shape

• Straight (b) and twisted (c) chain segments are

generated when the backbone carbon atoms (dark
circles) are oriented as in the figure above.
• Chain bending and twisting are possible by rotation
of carbon atoms around their chain bonds.
• Some of the polymer mechanical and thermal
characteristics are a function of the chain segment
rotation in response to applied stresses or thermal
vibrations. 48
 Chain End-to-End Distance, r
• Representation of a single
polymer chain molecule that
has numerous random kinks
and coils produced by chain
bond rotations; it is very
similar to a heavily tangled
fishing line.
• “r” is the end to end distance
of the polymer chain which is
much smaller than the total
chain length.
49
 Degree of Polymerization, DP
 Average number of repeat units per polymer chain
 An way of quantifying the molecular length or size of a polymer.

H H H H H H H H H H H H
H C C (C C ) C C C C C C C C H
H H H H H H H H H H H H
6 repeating units in the polymer chain DP = 6

50 repeating units in the polymer chain DP = 50

How to calculate DP?

Mol. Weight (Polymer) = DP × Mol. Weight (Repeat Unit)
Mol. Weight (Polymer)
DP = Mol. Weight (Repeat Unit)
If we know, the mol. weight of a polymer, and its repeating unit
 Polymer property depending on DP

Polystyrene,
DP = 7, a viscous liquid (not of much use commercially),
DP = 1000, a solid (commercial grade polystyrene)

Problem:
1. Mol. weight of polyethylene is 1,40,000. What is the degree of polymerization?

2. What is the molecular weight of polypropylene (PP), with a degree of

polymerization of 3×104?

Structure of the repeating unit for PP

Molecular weight of repeat unit = (3×12 + 6×1) = 42

Molecular weight of polypropylene = 3×104×42 = 1.26×106
Polymer Chain conformational change

Structural properties of linear

polymers: conformational
flexibility and strength

52
Representation of polymer architectures

(a) star polymer

(c)ladder polymer (d) semi- ladder

(or stepladder) polymer
Representation of polymer architectures
Representation of polymer architectures

(e) polyrotaxane (f) polycatenane

(g) dendrimer
Representation of polymer architectures
Representation of polymer architectures
 Molecular Weight of Polymer

• Molecular weight, M: Mass of a mole of chains.

Low Mol. Wt.

high Mol. Wt.

• Polymers can have various lengths depending on the number of repeat
units.

• During the polymerization process not all chains in a polymer grow to

the same length, so there is a distribution of chain lengths i.e.
distribution of molecular weights. There are several ways of defining an
average molecular weight.

• The molecular weight distribution in a polymer describes the relationship

between the number of moles of each polymer species and the molar
mass of that species. 58
 MOLECULAR WEIGHT DISTRIBUTION
 Mol. wt. distribution affects the properties of polymer. Low mol. wt.
polystyrene behaves differently from high mol. wt. polystyrene.

 A sample of polystyrene having narrow mol. wt. range (50,000-60,000)

exhibit different properties from one that have wide range (50-1,00,000);
though the average molecular weight is same.

Number average molecular weight

 The number average molecular weight is the total weight/mass
of the polymer sample divided by the number of molecules in
the sample.
Total mass of polymer NiMi
Number average mol. wt. Mn = =
Total number of polymer Ni

Ni = Number of molecules
Mi = Weight of each molecule = XiMi
NiMi = Total mass of polymer sample Number fraction = Xi
Mn =  (number fraction of each polymer x total mass of each polymer)
 Number average molecular weight
Xi Xi  Mi

Xi = Number fraction of each type molecule

60
 Weight average molecular weight
Wt. ave. mol. wt. =  (weight fraction of each type polymer x mass of each type polymer)

Mw = wiMi

wi = Weight fraction of each type polymer molecule

Weight of each type polymer NiMi
= =
Total mass of polymer sample NiMi

 NiMi2
Weight average mol. wt. = wiMi =
NiMi

Ni = Number of molecules
Mi = Weight of each type of molecules
NiMi = Total mass of polymer sample
Weight average molecular weight

Wi = Weight fraction

62
Number-average molecular weight (n)
Weight-average molecular weight (w)
Example - a polymer sample consists of 9 molecules of
mw 30,000 and 5 molecules of mw 50,000

Consider the previous example - 9 moles of molecular

weight 30,000 and 5 moles of molecular weight 50,000

Consider the previous example - 9 g of molecular

weight 30,000 and 5 g of molecular weight 50,000
 MOLECULAR WEIGHT
5 polymer chains of equal length
each chain contains 40 repeating unit
Mass of one repeating unit = 28 (-CH2 CH2-)

Total number of polymer = 5

Total Mass = 28 x 40 x 5 = 5600
Mol. wt. of one polymer = 28 x 40 = 1120

Total mass of polymer

Number average mol. wt. =
Total number of polymer

NiMi 5600
= = = 1120
Ni 5
 MOLECULAR WEIGHT

Total number of polymer molecule = 5

Mol. wt. of each polymer molecule = 28 x 40 = 1120
Total Mass = 28 x 40 x 5 = 5600

Weight fraction of 1st polymer, X1 = 1x1120/5600 = 0.2

Weight fraction of 2nd polymer, X2 = 1x1120/5600= 0.2
So on…………. 3rd X3 = 1x1120/5600= 0.2
4th X4 = 1x1120/5600 = 0.2
5th X5 = 1x1120/5600 = 0.2

Weight average mol. wt. =  (weight fraction of each polymer x total mass of polymer)
= XiMi
= 0.2x1120 + 0.2x1120 + 0.2x1120 + 0.2x1120 + 0.2x1120
= 1120
 MOLECULAR WEIGHT
 5 polymer chains of different lengths
 Each chain contains different number of
repeating unit.
 Mass of one repeating unit = 25

Polymer no Mol. wt.

1 (violet) 50
2 (green) 450
3 (orange) 1000
4 (cyan) 1500
5 (blue) 3000
Total 6000

Total mass of polymer 6000

Number average mol. wt. = = = 1200
Total number of polymer 5
 Polymer no Mol. wt. wt fraction of each mol.
1 (violet) 50 1x50/6000 = 0.0088
2 (green) 450 1x450/6000 = 0.075
3 (orange) 1000 1x1000/6000 =0.16
4 (cyan) 1500 1x1500/6000 = 0.25
5 (blue) 3000 1x3000/6000 = 0.5
Total 6000

Weight average mol. wt. =  (weight fraction of each polymer x total mass of polymer)

= 0.0088x50 + 0.075x450 + 0.16x1000 + 0.25x1500 + 0.5x3000

=2065
 MOLECULAR WEIGHT
Polymer Number of polymer Mol. wt.
type mol.
(violet) 4 50
(green) 5 450
(orange) 3 1000
(cyan) 5 1500
(blue) 3 3000
 MOLECULAR WEIGHT DISTRIBUTION
total wt of polymer
Mn 
total no. of molecules

NiMi
Mn = Ni

 NiMi2
Mw = xiMi =
NiMi

Weight average mol. wt. =  (weight fraction x total mass of polymer)

69
Molecular weight distribution
Here are:
10 chains of 100 molecular weight
20 chains of 500 molecular weight
40 chains of 1000 molecular weight
5 chains of 10000 molecular weight

(10 100)  (20  500)  (40 1000)  (5 10000)

Mn   1347
10  20  40  5

(10 100 2 )  (20  500 2 )  (40 1000 2 )  (5 10000 2 )

Mw   5390
(10 100)  (20  500)  (40 1000)  (5 10000)

Mw
Polydisper sity  4
Mn
 Polydispersity Index (PDI)
 PDI is a measure of the distribution of molecular
mass in a given polymer sample.
 It indicates the distribution of individual molecular
masses in a batch of polymers.
 The PDI is calculated by dividing the weight average
mol. weight by the number average mol. weight .

PDI = Mw/Mn

The PDI has a value always greater than 1, but as the

polymer chains approach uniform chain length, the PDI
approaches to unity (1). For some natural polymers PDI
is almost taken as unity.
Molecular wt. distribution based on PDI

PDI is low (nearly 1) PDI is high (>> 1)