Problem 189 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

The product of addition polymerisation reaction is (a) polythene (b) glyptal (c) nylon (d) terylene

Step-by-Step Solution

Answer

The product is polythene, formed from addition polymerization.

Step 1: Define Addition Polymerization

Addition polymerization is a type of polymerization where monomers add together without the loss of any atoms. The most common example of addition polymerization involves alkenes, which polymerize via their double bonds.

Step 2: Understand Polythene Formation

Polythene is formed from ethene (ethylene) monomers through addition polymerization. During this process, thousands of ethene molecules link together via their double bonds to form long chains of polythene.

Step 3: Contrast with Other Polymers

Glyptal, nylon, and terylene are all formed by condensation polymerization, not addition polymerization. In condensation polymerization, small molecules are released as byproducts, which is not the case in addition polymerization as seen with polythene.

Step 4: Determine the Correct Answer

Since polythene is formed via addition polymerization of ethene, the reaction in question results in the production of polythene.

Key Concepts

Polythene Formation

Polythene, also known as polyethylene, is a synthetic polymer made from the polymerization of ethene, also called ethylene. This process falls under the category of addition polymerization. During polythene formation, ethene molecules, which are simple hydrocarbons containing a carbon-carbon double bond, undergo a reaction where these double bonds break.
By breaking the double bonds, each ethene molecule can join with others to create long chains, forming polythene. This process is notable because it doesn't produce any byproducts; all atoms from the starting material (ethylene) are retained in the final polymer structure.
Polythene is widely used due to its versatility, being a key material for plastic bags, containers, and various other applications thanks to its durability and flexibility.

Condensation Polymerization

Condensation polymerization is a process where monomers join together to form polymers, but unlike addition polymerization, it involves the simultaneous loss of small molecules, often water or alcohol. This reaction typically occurs between monomers that possess two functional groups which react with one another.
Common examples of condensation polymers include glyptal, nylon, and terylene. Each has specific industrial uses: for instance, nylon is known for its strength and elasticity, making it ideal for textiles. Terylene finds applications in the production of polyester fibers, which are resistant to wrinkles and shrinkage.
The presence of byproducts is a crucial aspect of condensation polymerization. These byproducts can affect the properties of the final polymer, sometimes requiring additional processing to remove them or to use them constructively.

Difference Between Addition and Condensation Polymerization

While both addition and condensation polymerization are routes to creating polymers, they do so in fundamentally different ways. In addition polymerization, monomers add together without generating any byproducts. This method usually involves monomers with unsaturated bonds, such as the double bonds present in alkenes like ethylene.
Conversely, condensation polymerization always results in the formation of a small molecule byproduct. This characteristic difference often hinges on the type of monomers involved, which typically contain functional groups that react with one another.
This difference in mechanism leads to distinctive properties in the resulting polymers. Addition polymers, like polythene, are generally known for being simpler and more chemically inert. Meanwhile, condensation polymers have structures that may include various chemical groups, endowing these materials with a broader range of additional properties, such as increased strength or elasticity.