Polymers  

What is Polymers

Polymer is a term composed of two words i.e poly which means many and mer which means unit. Thus polymer is a bigger molecule made up of various smaller molecules, therefore polymers are also known as macromolecules. Some examples of polymers or macromolecules are  polyethene, DNA, protein, Nylon 6,6, etc. The process of formation of polymers by joining the structural units is known as polymerisation.

In this chapter, you will study the various types of polymers that are always around us and play a vital role in our life. Some of the real-life applications of polymers are described below:

  • Polycarbonate is one of the most important polymers. It is used for making eyeglasses.
     


Polymers example

 

  • Another polymer is polyamide. Because of its unique properties like durability, moisture resistant, temperature resistance, etc, it is widely used in making the parachutes.



polyamide example

 

  • DNA or deoxyribonucleic acid is one such important polymer in the body. Its monomer unit is known as a nucleotide.
     


DNA

 

 

Notes for Polymers

In this section, you will study about the important topics of the chapter, overview, formulae and some important tips and guidelines for the preparation of the chapter at the best.

 

Important Topics

  • Classification of polymers

  • Types of polymerization reactions

  • The molecular mass of polymers

  • Biodegradable polymers

  • Polymers of commercial importance

 

Overview of the chapter

In this chapter, you will study the various types of polymers that we use in daily life. In the following section, the classification of polymers is done using different methods.

Classification of polymers

Polymers are classified on the basis of various categories as given below:

(i) Classification of polymers on the basis of source: In this category, polymers are classified on the basis of source of origin:

  • Natural Polymers: These are the polymers that are directly obtained from nature. For example, protein, starch, rubber, etc.

  • Semi-synthetic Polymers: These are those polymers that are prepared in the laboratory by making some modifications in the natural polymers. For example, cellulose nitrate, cellulose acetate, etc. 

  • Synthetic Polymers: These are completely man-made polymers and developed in the laboratory. Some common examples are plastic, nylon 6,6, etc.

(ii) Classification of polymers on the basis of structure of polymers: 

  • Linear Polymers: These are those polymers that have long and straight chains but no branches. Some common examples include high density polythene, polyvinyl chloride, etc.

    Linear Polymers

  • Branched-chain polymers: These are those polymers that have long chains but also have some branches. Some examples include low-density polythene.

    Branched-chain polymers

  • Cross-linked or Network polymers: These are the polymers that have a long straight chain but these chains are connected through the strong covalent bonds. Examples are bakelite, melamine, etc.
    Cross-linked or Network polymers

(iii) Classification of polymers on the basis of mode of polymerization:

  • Addition polymers: These are those polymers that are formed by the repeated addition of monomer. The addition polymers are of two types viz:
    (i) Homopolymers: These are the polymers that are formed by the addition of the same monomers. For example:

    \mathrm {nCH_{2}=CH_{2}\rightarrow (CH_{2}-CH_{2})_{n}}

    (ii) Copolymers: The polymers formed by the addition of different monomers are known as copolymers. For example Buna-S, Buna-N, etc.

  • Condensation polymers: These are those polymers that are formed by the repeated condensation reaction of two different bi-functional or tri-functional monomeric molecules. In these reactions, small molecules such as water, hydrogen chloride, etc eliminate. Some common examples include nylon 6,6, terylene, etc.

    \mathrm{nH_{2}N(CH_{2})_{6}NH_{2}\, +\, nHOOC(CH_{2})_{4}COOH\, \rightarrow \, [NH(CH_{2})_{6}NHCO(CH_{2})_{4}CO]_{n}\, +\, nH_{2}O}

(iv) Classification of polymers on the basis of molecular forces:

  • Elastomers: These are those types of polymers in which the polymer chains are weakly bound to each other. Because of this weak interaction, these polymers have the elastic property. Some crosslinks are also present between the chains due to which these polymers are able to regain their original position. Some examples include buna-S, buna-N, etc.

  • Fibers: These are thread forming polymers. These polymers have high tensile strength and high modulus. They have strong intermolecular forces and thus have crystalline nature. Some examples include polyamides, polyesters, etc. 

  • Thermoplastic polymers: These polymers have a long chain of molecules with some branches. These molecules have the property to be softening on heating and hardening on cooling. Their intermolecular forces of attraction are intermediate between elastomers and fibres. Some common examples include polythene, polystyrene, etc.

  • Thermosetting polymers: These are highly branched chain polymers. These polymers cannot be reused. Some common examples include bakelite, urea-formaldehyde resins, etc.

 

Types of polymerization reactions

There are basically two types of polymerization reactions that you have to study in this chapter.

  • Addition polymerization or chain-growth polymerization: In this type of polymerization reaction, the addition of the same or different type of monomers occurs. These monomers are unsaturated in nature and their addition leads to the long-chain polymers. Examples include high-density polyethylene, Teflon, etc.
     
  • Condensation polymerization or step-growth polymerization: In this type of polymerization reaction, the repetitive condensation reaction of two bi-functional monomers takes place. This polymerization reaction results in the elimination of small molecules like water, alcohol, etc. Some examples include nylon 6,6, terylene, etc.

 

The Molecular Mass of Polymers

The molecular mass of polymers differs in different samples. The size and mass of any polymer depend on the number of monomers present in the reaction mixture. The properties of polymers depend upon their size and mass. Thus the molecular mass of any polymer is always measured in terms of average.

Biodegradable polymers

Most of the polymers available to us are non-biodegradable. Thus it has been a major environmental issue to degrade these non-biodegradable polymers. These polymers take a very long time to degrade and thus create so many problems to the environment. To eliminate all these problems, some new biodegradable polymers have been developed as mentioned below:

  • Poly β-hydroxybutyrate – co-β-hydroxy valerate (PHBV
  • Nylon 2–Nylon 6

 

Polymers of Commercial Importance

Other than the polymers that have been described, there are further many more other polymers that commercial importance. These are described in the table below along with their uses.

Name of Polymer Monomer Uses
Polypropene Propene Manufacture of ropes, toys
Polystyrene Styrene wrapping material, manufacture of toys
PVC Vinyl chloride Manufacture of raincoats, handbags, water pipes
Urea-formaldehyde resin Urea and formaldehyde Manufacture of unbreakable cups 
Glyptal Ethylene glycol and Phthalic acid Manufacture of paints and lacquers
Bakelite Phenol and formaldehyde For making combs, electrical switches

 

How to prepare for Amines?

  • This chapter is part of organic chemistry. It is completely theory-based. You are not supposed to memorize any formula and numerical practice for getting the good hold on this chapter. 

  • In this chapter, you need to remember the names of some important polymers and you also need to take care of the classification section

  • This chapter is not very lengthy, it is easy and remembering the diagrams of polymers is not necessary.

 

Prescribed Books

For this chapter, first, the NCERT book is best for initial level preparation as well as for board exams. Now, after this, if you want to prepare for competitive exams like JEE and NEET, then these are the best books for you - Morrison and Boyd and R.K Gupta by Arihant publication. Meanwhile, in the preparation, you must continuously give the mock tests for the depth of knowledge. Our platform will help you to provide with the variety of questions for deeper knowledge with the help of videos, articles and mock tests.

 

Chemistry Chapter- wise Notes for Engineering and Medical Exams

Chapters No.

Chapters Name

Chapter 1

Some basic concepts in chemistry

Chapter 2

States of matter

Chapter 3

Atomic Structure

Chapter 4

Solutions

Chapter 5

Chemical Thermodynamics

Chapter 6

Equilibrium

Chapter 7

Redox Reaction and Electrochemistry

Chapter 8

Chemical kinetics

Chapter 9

Surface Chemistry

Chapter 10

General Principle and processes of Isolation of metals

Chapter 11

Classification of Elements and Periodic table

Chapter 12 

Hydrogen

Chapter 13

p- block Elements

Chapter 14 

s-block Elements (Alkali and Alkaline Earth Metals)

Chapter 15 

Chemical Bonding and Molecular Structure

Chapter 16

d- and f- BLOCK ELEMENTS

Chapter 17

Coordination Compounds

Chapter  18 

Environmental Chemistry

Chapter 19

Purification and Characterisation of Organic Compounds

Chapter 20

Some Basic Principles of Organic Chemistry

Chapter 21

Hydrocarbons

Chapter 22

Organic Compounds containing Halogens

Chapter 23

Organic Compounds containing Oxygen

Chapter 24

Organic Compounds Containing Nitrogen

Chapter 26

Biomolecules

Chapter 27

Chemistry in Everyday Life

Chapter 28

Principles Related to Practical Chemistry

Topics from Polymers

  • Introduction to polymers ( JEE Main ) (2 concepts)
  • Classification Based on Source ( JEE Main ) (3 concepts)
  • Classification Based on Structure of Polymers ( JEE Main ) (3 concepts)
  • Classification Based on Mode of Polymerisation ( JEE Main ) (4 concepts)
  • Classification Based on Molecular Forces ( JEE Main ) (5 concepts)
  • Classification Based on Growth Polymerisation ( JEE Main ) (2 concepts)
  • Types of polymerization reactions ( JEE Main ) (10 concepts)
  • Rubber ( JEE Main ) (6 concepts)
  • Biodegradable Polymers ( JEE Main ) (2 concepts)
  • Copolymerisation ( JEE Main ) (1 concepts)

Important Books for Polymers

  • Polymers Book
  • Polymers Book
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