During addition polymerisation of ethene molecules , the initiator like benzoyl peroxide , acetyl peroxide , tert-butyl peroxide , etc ., are added . Their function is to

Options

A. ensure anti-Markownikoff's addition of molecules to form polymer
B. give cations during the reaction which join together to form bigger molecules
C. decrease the temperature of the reaction mixture
D. generate free radical which adds to the monomer to give bigger free radical .

Explanation

To answer the question regarding the function of initiators like benzoyl peroxide, acetyl peroxide, and tert-butyl peroxide in the addition polymerization of ethene, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding Addition Polymerization**:
- Addition polymerization is a process where monomers (like ethene) are chemically bonded together to form a polymer. This process typically requires an initiator to start the reaction.

2. **Role of Initiators**:
- Initiators such as benzoyl peroxide, acetyl peroxide, and tert-butyl peroxide are compounds that decompose to generate free radicals. These free radicals are essential for initiating the polymerization process.

3. **Mechanism of Free Radical Generation**:
- When an initiator like benzoyl peroxide is heated or exposed to light, it decomposes to form free radicals. For example, benzoyl peroxide decomposes to produce two phenyl radicals:
\[ \text{Benzoyl peroxide} \rightarrow 2 \text{C}_6\text{H}_5\text{COO} \cdot \]

4. **Initiation of Polymerization**:
- The generated free radicals can react with ethene (or other alkenes) to form a new free radical. This reaction involves the addition of the free radical to the double bond of ethene, resulting in a larger free radical:
\[ \text{C}_6\text{H}_5\cdot + \text{C}_2\text{H}_4 \rightarrow \text{C}_6\text{H}_5\text{CH}_2\text{CH}_2\cdot \]
- This new free radical can further react with more ethene molecules, continuing the chain reaction.

5. **Conclusion**:
- The primary function of these initiators is to generate free radicals that initiate the polymerization process by adding to the monomer (ethene) and forming larger free radicals, which can then continue to react with additional monomers.

### Final Answer:
The correct option is that the function of initiators like benzoyl peroxide is to **generate free radicals which add to the monomer to give bigger free radicals**.

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