A large number of simple molecules called monomers combine together to form a macromolecule called a polymer. Each polymer has a repeating structural unit. If the repeating structural unit is derived from one type of monomer molecules. The polymer is said to be a homopolymer and if it is derived from two or more different types of monomer molecules , the polymer is said to be a copolmer. Both homopolymers and copolymers may be formed either by addition or condensation reactions. Alkenes and dienes polymerize by addition (chain growth) mechanism involving carbocations , carbanions or free radical intermediates. Dienes (chloroprene, isoprene, etc.) polymerize by 1, 4-addition mechanism to give cis-or trans-polymers. Natural rubber is quite soft and tacky but these properties can be improved by a process called vulcanization.
In contrast , bifunctional monomer molecules undergo , condensation or step-growth polymerization. Polymers which can be heated and reshaped as many times as desired are called thermoplastics , (polythene, polystyrene, PVC, teflon, etc.) while those which can be heated only once to give a particular shape are called thermosetting polymers (bakelite, melmac, etc.).
Which of the following sets contain only copolymers ?

Options

A. SBR, Glypal, Nylon6,6
B. Nylon 6, Butyl rubber, Neoprene
C. Polythene, Polyester , PVC
D. Melmac, Bakelite , Teflon

Answer

To determine which set contains only copolymers, we need to analyze the definitions and examples of copolymers and homopolymers. Here’s a step-by-step solution:

### Step 1: Understand the Definitions
- **Monomers** are small molecules that can join together to form polymers.
- **Homopolymers** are polymers made from one type of monomer.
- **Copolymers** are polymers made from two or more different types of monomers.

### Step 2: Identify Examples of Polymers
- **SBR (Styrene-Butadiene Rubber)**: This is made from two different monomers, styrene and butadiene, making it a copolymer.
- **Gliptal**: This polymer is formed from ethylene glycol and phthalic acid, which are different monomers, thus it is also a copolymer.
- **Nylon 6-6**: This polymer is made from hexamethylene diamine and adipic acid, which are different monomers, making it a copolymer.

### Step 3: Identify Homopolymers
- **Polythene**: This is made from only one type of monomer, ethylene, hence it is a homopolymer.
- **Teflon**: This is made from tetrafluoroethylene, which is a single type of monomer, making it a homopolymer.

### Step 4: Analyze the Options
Given the analysis:
- **Option 1**: Contains SBR, Gliptal, and Nylon 6-6 (all copolymers).
- **Option 2**: Contains Polythene and Teflon (both homopolymers).

Thus, the correct answer is **Option 1**, which contains only copolymers.

### Final Answer
The set that contains only copolymers is **Option 1**.

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