Reversible Polymerization Reaction

some polymerization reactions are reversible. There is interest in reverse polymerization from Green chemistry angle. Also recently, it was proved by a Mumbai scientist, the a protein that form oligomers can be converted back into monomers by creating situation suitable for reverse polymerization. So concepts one learns in XI or XII class have applications in very important issues related human life.

Look at this small abstract

http://leishman.conference-services.net/resources/266/2152/pdf/32APS_0272.pdf

Polymers and Their Monomers

Polymer - Monomers


Homopolymers (Only one monomer)

Cellulose – Glucose
Natural rubber – Isoprene (2-metyl-1, 3-butadiene)

Neoprene - Chloroprene
Nylon-6 - caprolactum

Polyacrylonytrile (PAN) or Orlon – Vinyl cyanide (acrylonitrile)
Polyethelene - Ethylene (Ethene)
(Popularly polythene)
Polyethyl acrylate (PEA) - ethyl acrylate
Polymethyl methacrylate (PMMA) – Methyl methacrylate
Polymonochlorotrifluoroethylene (PCTFE) - chlorotri-fluoroehtylene
Polypropylene – Propylene
Polystyrene or Styron – styrene
Polytetrafluoroethylene (Teflon or PTFE) - tetrafluoroethylene
Polyvinyl chloride – Vinyl chloride
Proteins - Alpha-Amino acids

Starch - Glucose


Copolymers (Two different monomers)

Bakelyte (Phenol formaldehyde resin) - Phenol and Formaldehyde
Buna-S - 1,3-butadiene and styrene
Dacron (Polyster) - Terephthalic acid and ethylene glycol
Glyptal - ethylene glycol and phthalic acid
Melamine polymer (Melamine formaldehyde) - Melamine and fromaldyhyde
Nylon-66 - Hexamethylenediamine and adipic acid
Saran - vinyl choride and vinylidene chloride
Styrene-butadiene rubber - styrene and 1,3-butadiene
Thiokol - 1,2 dichlorlethene (ethylene dichloride) and sodium polysulphide
Terylene - ethylene glycol and terephthalic acid

Difference Between a Metal and Polymer

In the chapter in polymers, it is explained that polymers are compounds of very high molecular masses formed by the combination of a large number of simple molecules. Simple example of a polymer is polyethelene. This polymer is formed by the compound formation between molecules of ethelene. The molecules of ethylene in the case of formation of polymer are referred to as monomers.

But what is the difference between a metal and polymer?

Metal

At a molecular level, the basic units that make up a metallic structure are relatively small and uniform in size. Consequently, they readily arrange into a structure that is very regular and predictable. Material scientists call these structures as crystalline solids.


Polymer

The smallest unit in a polymeric material is a very large molecule with an extended chain shape. (Remember linear chains, branched chains and cross linked chains). Even the smallest polymer molecule will be about 50 times more massive than the heaviest naturally occurring unit in a metallic structure. These polymer molecules can twist, turn, fold, and entangle in almost unlimited variations (Remember the point regarding straightening of chains due to stretching). In addition, not all of these molecules are of the same size. The smallest molecule in any random sample of plastic is often a thousand times smaller than the largest, which increases the possibilities for local variation in the structure of a material.


In a metal there ionic forces between free flowing electrons and the positive charged nucleuses that hold the metal together. In a polymer there are covalent bonds between molecules of various sizes, with each molecule being polymer of number of monomers.

JEE - Study Guide - 16. Polymers

Sections in the chapter - Jauhar

16.1 Polymers
16.2 Classification of Polymers
16.3 General methods of Polymerisation
16.4 Mechanism of addition Polymerisation
16.5 Copolymers
16.6 Natural rubber
16.7 Condensation of Polymers
16.8 Molecular masses of Polymers
16.9 Biopolymers
16.10 Biodegradable Polymers
16.11 Some Commercially important Polymers

Practice problems 16.1 to 16.3
Conceptual Questions with Answers: 10
Additional Numerical Problems for Practice:
Revision Exercises
Very Short Answer questions 26
Short Answer Questions 53

Competition File
Numerical Problems
Objective Questions: Multiple choice 22
Fill in the blanks: 10
True or False: 10

Study Plan

Day 1

16.1 Polymers
16.2 Classification of Polymers
16.3 General methods of Polymerisation

Day 2
16.4 Mechanism of addition Polymerisation
16.5 Copolymers
16.6 Natural rubber

Day 3
16.7 Condensation of Polymers
16.8 Molecular masses of Polymers
16.9 Biopolymers
16.10 Biodegradable Polymers
Day 4

16.11 Some Commercially important Polymers


Day 5
Practice problems 16.1 to 16.3
Conceptual Questions with Answers: 10
Revision Exercises: Very Short Answer questions 1 to 15

Day 6
Revision Exercises: Very Short Answer questions 16 to 26

Day 7
Revision Exercises: Short Answer Questions 1 to 30

Day 8
Revision Exercises: Short Answer Questions 31 to 53

Day 9
Competition File: Objective Questions: Multiple choice 22
Fill in the blanks: 10
True or False: 10

Day 10
Concept Revision

Days 11 to 20
Test paper question solving