Polymer Chemistry
MBM 471
Lecture 1: Introduction
Faculty Asst. Prof. İlke Anaç (e-mail:[email protected])
Room: 212
Content-1
Introduction: Basic concepts and definitions, classification of
polymers, nomeculature of polymers, molecular weight and its
distribution

Polymerization mechanisms: Chain polymerization
-Free radical polymerization
-Cationic polymerization
- Anionic polymerization
Step- growth polymerization, ring-opening polymerization,
coordination polymerization
Chemical bonding and polymer structure, polymer molecular weight
Thermal transitions in polymers
Polymer modification: Copolymerization, post polymerization
reactions and functional polymers
Content-2
Polymer additives and reinforcements
Polymerization techniques
Polymer processing: an overview of processing
techniques for thermoplastics and thermosets
Solution properties of polymers
Mechanical properties of polymers
Polymer viscoelasticity
Assesment
Midterm- %35 (November 16)
Final: %50
Quiz- %10 (4 quiz)
Attendence % 5
Textbook
• Textbook: Polymer Science and Technology, Robert O Ebewele
(CRC press, New York,2000)
•
Additional Books: Introduction to Polymers, R.J. Young and P. A.
Lowell (Stanley Thornes, 2nd edition)
• Polymer Science & Technology, Joel R. Fried, Prentice Hall, 2nd
edition
• Polymer Kimyası, Prof. Dr. Mehmet Saçak, Gazi Yayınevi, 5. baskı
• Polymer Teknolojisi, Prof. Dr. Mehmet Saçak, Gazi Yayınevi, 5.
baskı
Historical Background
Ages ago - Natural Fibers Ex. Wool, silk, cotton
In 1736, Charles Marie de La
Condamine introduced the para
rubber tree (natural rubber).
Hevea brasiliensis
Natural (hevea) rubber known as
polyisoprene in its synthetic form.
“Crying tree”
(para rubber)
Latex Coating
Historical Background
1839-Charles Goodyear
Vulcanization: Transformation of sticky natural rubber to a useful
elastomer for tire use
S8
1843-Charles Goodyear
Ebonite High % vulcanization
(1st synthetic plastic made from natural rubber)
Fountain pen bodies
smoking pipe mouthpiece
bowling balls
Synthetic Polymers Started
1847
“Cellulose
nitrate”
cellulose
cellulose nitrate
1860s -Parkes (Electrical industry) and Hyatt (Billiard balls)
“Celluloid”
(1st artificial thermoplastic)
Cellulose nitrate+ Camphor (as plasticizer)
1907-Leo Baekeland “Bakelite”
(thermosetting phenol-formaldehyde resin)
Bakelite letter opener
Bakelite radio
On further heating with HCHO, novalac undergoes cross-linking to an infusible solid called bakelite. It is hard scratch and water resistant.
Bakelite telephone
1st truly synthetic plastic
Bakelite distributor rotor
Nobel Prize-Chemistry 1953 for “his discoveries in the field of macromolecular chemistry”
1920 “Macromolecular Hypothesis”
Demonstrations of both synthetic and natural polymers
Polymer is a giant molecule
long chains of short repeating
molecular units linked by covalent bonds
Hermann Staudinger
A chain of paper clips (above) is a good
model for a polymer such as polylactic acid (below).
Between 1925-1950
Phenomenal growth in the number of polymeric products that achieved commercial use
1950`s acetal and polycarbonates (automotive and appliance parts)
1960s-1970s- thermoplastic polyesters (exterior automotive parts, bottles), high barrier nitrile resins and
high temperature plastics including materials such as polyphenylene sulfide, polyether sulfone.
Definitions
Polymer science is relatively a new branch of science . It deals with chemistry
physics and mechanical properties of macromolecule .
Polymer –is a large molecule consisting of a number of repeating
units with molecular weight typically several thousand or higher
Polymers are made up of many Monomers
Many units
One units
Repeating unit – is the fundamental recurring unit of a polymer
Monomer - is the smaller molecule(s) that are used to prepare a
polymer
Oligomer –is a molecule consisting of reaction of several repeat
units of a monomer but not large enough to be consider a polymer
(dimer , trimer, tetramer, . . .)
Degree of polymerization (DP)- number of repeating units
1
2
3
Nylon 6,6
POLYETHYLENE
Zig-zag conformation
Substituent groups such as –CH3, -OCOCH3, CN, Cl or –Ph that are attached
to the main chain of the skeletal atoms are known as pendant groups. Their
structure and chemical nature can offer unique properties on polymer.
Classification of Polymers
A. Classification by Origin
• Natural Polymers
-Biological Origin - enzymes, nucleic acids, proteins
-Plant Origin – cellulose, starch, natural rubber
•Synthetic Polymers
- Fibers
- Elastomers
- Plastics
-Adhesives
3.Classification by Polymerization Mechanism
Classification of polymers to be suggested by Carothers
Addition polymers are produced by reactions in which monomers are added
one after another to a rapidly growing chain. Most important addition polymers
are polymerized from ethylene based polymers.
•Initiation
•Propagation
Unsaturated (C-C double bond)
(ethylene based monomers)
•Termination
Ring opening polymerization
Polyoxymethylene
Trioxane
2.Classification by Polymerization Mechanism
Condensation polymers are obtained by random reaction of two molecules.
A molecule participating in a condensation reaction may be a monomer, oligomer, or high molecular
weight intermediate each having complementary functional end units, such as carboxylic acid or
hydroxyl groups. Typically condensation polymerizations occur by the liberation of a small molecule in
the form of gas, water, or salt.
More recently, another classification scheme based on polymerization kinetics has been adopted
over the more traditional addition and condensation categories.
•
Step growth
•
Chain growth
3.Classification by Polymer Structure
Classification by Chain structure (molecular architecture)
The architecture of the polymer is often physically determined by the functionality of the monomers
from which it is formed. This property of a monomer is defined as the number of reaction sites at which
may form chemical covalent bonds.
bifunctional
bifunctional
bifunctional
3.Classification by Polymer Structure
Classification by Chain structure (molecular architecture)
(a) linear
(b) branch
The basic functionality required for forming even a linear chain is two
bonding sites.
Higher functionality yields branched or even crosslinked or networked
polymer chains.
Branched polymers have side chains, or branches, of significant
points (known as junction points), are characterized in terms of the
number and size of the branches
(c) network
Network polymers have three dimensional structures in which each
chain is connected to all others by a sequence of junction points and
other chains. Such polymers are said to be crosslinked and
characterized by their crosslink density, or degree of crosslinking,
which is related to the number of junction points per unit volume
Non linear polymers may be formed by polymerization, or can be prepared by linking together (ex.
crosslinking) pre-existing chains.
2.Classification by Polymer Structure
Classification by Chain structure (molecular architecture)
(d) ladder polymer
Ladder polymers constitute a group of polymer with a regular sequence of crosslinks.
diacetylene
2.Classification by Polymer Structure
Classification by Chain structure (molecular architecture)
(g) dendrimer
Dendrimers are repeatedly branched, roughly
spherical large molecules.
4.Classification by Polymer Structure
Classification by Monomer Composition
A. Homopolymer -contain only one type of repeat unit (A))
B. Copolymer -contain two different repeating units (AB)
If there are three chemically different repeating unit, it is then called terpolymer
Poly(styrene-co-acrylonitrile) (SAN)
Type of Copolymers
Random copolymer : -A-B-B-A-B-A-A-B-two or more different repeating unit are distributed randomly
Alternating copolymer : -A-B-A-B-A-B-A-B-are made of alternating sequences of the different monomers
Block copolymer :
-A-A-A-A-B-B-B-B-long sequences of a monomer are followed by long sequences of
another monomer
B-B-B-B-BGraft copolymer : -A-A-A-A-A-A-A-A-Consist of a chain made from one type of monomers with branches
of another type
5.Classification by Thermal Behavior
A thermoset is a polymer that, when heated, undergoes a chemical change to produce a
cross-linked, solid polymer.( Ex: urea-formaldehyde, phenol-formaldehyde, epoxies)
Thermoplastic polymers soften and flow under the action of heat and pressure. Upon
cooling, the polymer hardens and assumes the shape of the mold (container).
(Ex: polyethylene, polystyrene, and nylon)
6.Classification by Preparative Technique
A) Bulk polymerization-only the monomer (and possibly catalyst and initiator, but no solvent) is
fed into the reactor. The monomer undergoes polymerization, at the end of which a (nearly) solid
mass is removed as the polymer product.
B) Solution Polymerization- involves polymerization of a monomer in a solvent in which both
the monomer (reactant) and polymer (product) are soluble
C) Suspension Polymerization- refers to polymerization in an aqueous medium with the
monomer as the dispersed phase. Consequently, the polymer resulting from such a system forms
a solid dispersed phase.
D) Emulsion Polymerization- is similar to suspension polymerization but the initiator is located
in the aqueous phase (continuous phase) in contrast to the monomer (dispersed phase) in
suspension polymerization.
Inorganic Polymers
Cl
CH3
O
N
Si
P
n
n
Cl
CH3
Poly(dichlorophosphazene)
polydimethylsiloxane
Polyelectrolytes
CH3
H2
C
H2
C
H
C
C
n
n
COOH
COOH
Poly(acrylic acid)
Poly(methacrylic acid)
MOLECULAR WEIGHT
The degree of polymerization represents one way of quantifying the molecular length or size of
a polymer. This can also be done by use of the term molecular weight (MW). By definition,
MW(Polymer) = DP × MW(Repeat Unit).
A number-average molecular weight Mn : divide
chains into series of size ranges and then determine the
number fraction Ni of each size range
Mn = ∑ Mi Ni / ∑ Ni
where Mi represents the mean molecular weight of the
size range i, and Ni is the fraction of total number of
chains within the corresponding size range
A weight average molecular weight Mw is based on
the weight fraction wi within the size range.
Mw = ∑ Mi Wi / ∑ Wi
Polydispersity Index (PDI)
A measure of the molecular-weight distribution is given by the ratios of molecular
weight averages.
For this purpose, the most commonly used ratio is Mw/Mn, which is called the
polydispersity index or PDI.
PDI= Mw/Mn
Mw/Mn = 1
monodisperse
Polymer sample consisting of molecules all of which have the same chain length.
Mw/ Mn > 1
polydisperse
Polymer consisting of molecules with the variety of chain length
Nomenclature
A. Types of Nomenclature
a. Source name : to be based on names of corresponding monomer
Polyethylene, Poly(vinyl chloride), Poly(ethylene oxide)
b. IUPAC name : to be based on CRU, systematic name
Poly(methylene), Poly(1-chloroethylene), Poly(oxyethylene)
c. Functional group name :
According to name of functional group in the polymer backbone
Polyamide, Polyester
Nomenclature
d. Trade name : The commercial names by manufacturer Teflon, Nylon
e. Abbreviation name : PVC, PET
f. Complex and Network polymer : Phenol-formaldehyde polymer
Vinyl polymers
A. Vinyl polymers
a. Source name : Polystyrene, Poly(acrylic acid),
Poly(α-methyl styrene), Poly(1-pentene)
b. IUPAC name : Poly(1-phenylethylene), Poly(1-carboxylatoethylene)
Poly(1-methyl-1-phenylethylene), Poly(1-propylethylene)
Polystyrene
Poly(acrylic acid)
CH2CH
CH2CH
CO2H
Poly(α-methylstyrene)
Poly(1-pentene)
CH3
CH2C
CH2CH
CH2CH2CH3
Vinyl polymers
B. Diene monomers
CH 2CH
HC
CH 2CH
CHCH 2
CH 2
1,2-addition
1,4-addition
Source name : 1,2-Poly(1,3-butadiene) 1,4-Poly(1,3-butadiene)
IUPAC name : Poly(1-vinylethylene)
Poly(1-butene-1,4-diyl)
Vinyl copolymer
Type
Connective
Example
Unspecified
-co-
Poly[styrene-co-(methyl methacrylate)]
Statistical
-stat-
Poly(styrene-stat-butadiene)
Random
-ran-
Poly [ethyelene-ran-(vinylacetate)]
Alternating
-alt-
Poly[styrene-alt-(maleic anyhride)]
Block
-block-
Polystyrene-block-polybutadiene
Graft
-graft-
Polybutadiene-graft-polystyrene
* A statistical polymer is one in which the sequential distribution of the monomeric units obeys the statistical laws. In the case of random copolymer, the
probability of finding a given monomeric unit at any site in the chain is independent of the neighboring units in that position.
Polystyrene-block-polybutadiene
Polystyrene-graft-polybutadiene
* Representative Nomenclature of Nonvinyl Polymers
Monomer
structure
Polymer
repeating unit
Source or
Common Name
IUPAC name
O
H2C
CH2
HOCH2CH2OH
CH2CH2O
CH2CH2O
Poly(ethylene glycol)
O
H2N(CH2)6NH2
HO2C(CH2)8CO2H
Poly(ethylene oxide)
Poly(oxyethylene)
Poly(oxyethylene)
O
NH(CH2)6NHC(CH2)8C
Poly(hexamethylene
Poly(iminohexanesebacamide) or Nylon6,10 1,6-diyliminosebacoyl)
Abbreviations
Abbreviation
Name
PVC
Poly(vinyl chloride)
HDPE
High-density polyethylene
LDPE
Low-density polyethylene
PET
Poly(ethylene terephthalate)
ABS
Arcylonitrile-butadiene-styrene resin
PBT
Poly(butylene terephthalate)
PE
Polyethylene
PMMA
Poly(methyl methacrylate)
PP
Polypropylene
PS
Polystyrene
PTFE
Poly(tetrafluoroethylene)
PEO
Poly(ethylene oxide)