Hari Om SURESH DANI’s CLASSES JSK XII – CHEMISTRY – THEORY + MCQS CHAPTER NO - 15 – INTRODUCTION TO POLYMER CHEMISTRY (Weightage : 04 Marks) (Advance Batch Notes: YEAR - 2020) Introduction to Polymer Page 1 of 29 PART: I – INTRODUCTION Chemistry plays a very important role in day to day life. There are different types of branches comes under chemistry. Polymer chemistry emerged as a separate branch of chemistry during the last several decades due to the voluminous knowledge built up in this field and the ever increasing applications in everyday life. The term “Polymer” was coined in 1833 by Berzelius while performing cellulose derivative experiments. MEANING OF MONOMER : The term 'monomer' originates from Greek word 'mono' meaning single or one and 'mer' meaning part or unit. i.e. (single unit /single part 0r one unit/one part) DEFINITION OF MONOMERS : A lower molecular weight molecule capable of reacting with identical or different molecules of low molecular weight to form a polymer are called as Monomers. OR The simple molecules which combined to form a polymers are called Monomers. MEANING OF POLYMER : The term 'polymer' originates from Greek word 'poly' meaning many or more and 'meros' meaning part or unit. i.e. (Many unit / Many part 0r More unit/More part) DEFINITION OF POLYMERS : Polymers are high molecular mass macromolecules (10 3 – 10 7 u) made from repeating units of monomers. EXAMPLES: Name Of Monomer Name of Polymer 1. Glucose Starch 2. Glucose Cellulose 3. Aminoacids Protein 4. Nucleotide Nucleic acid(DNA)/(RNA) 5. Ethene Polyethene 6. Vinylchloride Polyvinylchloride (PVC)
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Hari Om SURESH DANI’s CLASSES JSK
XII – CHEMISTRY – THEORY + MCQS
CHAPTER NO - 15 – INTRODUCTION TO POLYMER CHEMISTRY
(Weightage : 04 Marks) (Advance Batch Notes: YEAR - 2020)
Introduction to Polymer Page 1 of 29
PART: I – INTRODUCTION
Chemistry plays a very important role in day to day life.
There are different types of branches comes under chemistry.
Polymer chemistry emerged as a separate branch of chemistry during the last several decades due
to the voluminous knowledge built up in this field and the ever increasing applications in everyday
life.
The term “Polymer” was coined in 1833 by Berzelius while performing cellulose derivative
experiments.
MEANING OF MONOMER :
The term 'monomer' originates from Greek word 'mono' meaning single or one and 'mer' meaning
part or unit.
i.e. (single unit /single part 0r one unit/one part)
DEFINITION OF MONOMERS :
A lower molecular weight molecule capable of reacting with identical or different molecules of low
molecular weight to form a polymer are called as Monomers.
OR The simple molecules which combined to form a polymers are called Monomers.
MEANING OF POLYMER :
The term 'polymer' originates from Greek word 'poly' meaning many or more and 'meros' meaning
part or unit.
i.e. (Many unit / Many part 0r More unit/More part)
DEFINITION OF POLYMERS :
Polymers are high molecular mass macromolecules (103 – 107 u) made from repeating units of monomers.
EXAMPLES:
Name Of Monomer Name of Polymer
1. Glucose Starch
2. Glucose Cellulose
3. Aminoacids Protein
4. Nucleotide Nucleic acid(DNA)/(RNA)
5. Ethene Polyethene
6. Vinylchloride Polyvinylchloride (PVC)
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Introduction to Polymer Page 2 of 29
REPRESNTATION OF POLYMERS:
Monomer Repeating units of Monomer Representation of Polymer
1. n A –(A)– –[A]n–
2. n A + n B –(A-B)– –[A-B]n–
3. n A + n B + n C –(A-B-C)– –[A-B-C]n–
4. n CH2 = CH2
Ethene
–(CH2 – CH2)– –[ CH2 – CH2]n–
Polythene
5. n CH2 =CH – CH= CH2
Buta – 1,3 –diene
+
n CH2 =CH – CN
Acrylonitrile
–(CH2 –CH = CH–CH2–CH2–CH)–
CN
–[CH2 –CH = CH–CH2–CH2–CH]n–
CN
Buna - N
DEFINITION OF POLYMERIZATION:(PROCESS)
The process by which the simple molecules (i.e. monomers) are converted into polymers is called
polymerization.
OR
A process of synthesizing polymers from repeating units of monomers is called as polymerization.
i.e. PolymerizationMonomer Polymer
Example: Transformation of ethene to polythene.
Polymers are Inorganic (Ex. Silicones) as well as organic (Ex.Polythene).
Organic biopolymers (Ex.Starch) playing crucial role in living world.
NOTE:
All polymers are macromolecules but all macromolecules are not polymers because
macromolecules do not contain repeating units of monomers.
Example: Haemoglobin and Chlorophyll are macromolecules but are not polymer because
Haemoglobin and Chlorophyll do not contain repeating units of monomers.
PART – I – EXERCISE: IMPORTANT QUESTION – (EACH QUESTION – 2 Mark)
1. Define Monomers. Write its example.
2. Define Polymers. Write its example.
3. Define Polymerization. [ 1 M ]
4. Write the structural representation of following polymers:
a) Polythene b) Buna – N
5. Write the name of monomer used to prepare following polymers:
a) Starch b) Proteins
c) DNA d) Polyvinylchloride(PVC)
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Introduction to Polymer Page 3 of 29
PART: II – CLASSIFICATION OF POLYMERS
Polymers are classified in a number of ways as mentioned below:
1. Classification based On Source or Origin
2. Classification based On Structure
3. Classification based On Mode Of Polymerization
4. Classification based On Intermolecular forces
5. Classification based On Type of Monomers
6. Classification based On Biodegradability
7. Classification based On growth polymerization (Not in G. text book refer NCERT )
1. CLASSIFICATION BASED ON SOURCE OR ORIGIN:
On the basis of source, polymers are classified into the following three categories:
i. Natural polymers:
The polymers obtained from nature are called natural polymers.
They are further subdivided into two types: Plant polymers and Animal polymers.
Plant Polymers Animal Polymers
These are obtained from plants. These are derived from animal sources.
For example:
Cotton : Cotton plant
Linen : Flax plant
Natural rubber : (latex)Bark of rubber trees
Jute : Vegetable fibres
Starch : Carbohydrates
Cellulose : Wood pulp
For example:
Wool : Sheep
Silk : Silkworm
Leather: Animal silk
ii. Semi-synthetic polymers:
The properties of natural polymers such as appearance, tensile strength, lustre, etc are
modified by some chemical treatment, to obtain semi-synthetic polymer.
These are also called regenerated fibres.
Example: Cellulose derivatives such as cellulose acetate rayon, cellulose nitrate, viscose
rayon, cuprammonium rayon etc
Semisynthetic polymers are used in preparation of non-inflammable photographic films,
cinema films, varnishes, etc.
iii. Synthetic polymers:
The polymers which are synthesized in the laboratories or in the industries are called
synthetic polymers.
These are also called Man made polymers.
These are further divided into three subtypes, namely fibres, synthetic rubbers and
plastics.
Hari Om SURESH DANI’S CLASSES Jsk
Introduction to Polymer Page 4 of 29
Example:
Fibres Synthetic rubbers Plastics
Nylon – 6 Buna – S (SBR rubber) Polythene
Nylon – 6,6 Buna – N Polyvinylchloride(PVC)
Terylene (Dacron) Neo-prene Polypropene
- Butyl rubber Teflon
- - Orlon
- - Polystyrene
- - Bakelite
2. CLASSIFICATION BASED ON STRUCTURE:
On the basis of structure, polymers are divided into three types:
i. Linear or Straight chain polymers: [1 Dimensional structure]
A polymer formed by combination of repeating units of monomers having long continuous
chains without any excess attachments (branches) are called linear polymers.
It is obtained from bifunctional monomers or alkenes.
These are well packed and therefore, have high densities, high tensile strength and high
melting points.
Example:
Fibres Synthetic rubbers Plastics
Nylon – 6 Buna – N (SBR rubber) Polythene(HDPE)
Nylon – 6,6 Neo-prene Polyvinylchloride(PVC)
Terylene (Dacron) - Teflon
- - Orlon
ii. Branched chain polymers: [2 Dimensional structure]
A polymer formed by combination of repeating units of monomers having long continuous
chains with small attachments (branches) are called branched chain polymers.
It is obtained from Monomer having 3 functional groups or already having side chains.
These are irregularly packed and therefore have low density, low tensile strength and low
melting points than those of linear polymers.
Example: Starch , Cellulose
Fibres Synthetic rubbers Plastics
- Buna - S Polythene(LDPE)
- Butyl rubber Polypropylene
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Introduction to Polymer Page 5 of 29
iii. Crossed or Network linked polymers: [3 Dimensional structure]
A polymer formed by strong covalent bonds of repeating units of monomers and have
cross-network like structure are called Network linked polymers.
It is obtained from polyfunctional monomers.
These polymers are hard, rigid and brittle because of the network structure.
Example:
Fibres Synthetic rubbers Plastics
- Vulcanized rubber Bakelite
- - Melamine – formaldehyde
3. CLASSIFICATION BASED ON MODE OF POLYMERIZATION:
Polymerization is the fundamental process by which low molecular mass compounds are
converted into high molecular weight compounds by linking together of repeating structural
units with covalent bonds.
This process is illustrated below. _ _ Pr
_Low molecular mass material High molecular mass material
(Possessing reactive groups)
High temperature or essure
Or Catalyst
On the basis of Mode of polymerization, polymers are divided into three types:
i. Addition polymerization or chain growth polymerization:
Addition polymerization is a process of formation of polymers by addition of monomers
without loss of any small molecules.
The repeating unit of an addition polymer has the same elemental composition as that of
original monomer.
It is obtained from Monomer having Alkene and their derivatives.
It is also referred as vinyl polymerization, since majority of monomers are from vinyl