Which monomer would polymerise in isotactic syndiotactic and atactic forms?

Answer

To determine which monomer can polymerize into isotactic, syndiotactic, and atactic forms, we need to analyze the structural characteristics of the monomers involved.

### Step-by-Step Solution:

1. **Understanding Polymer Forms**:
- **Isotactic Polymers**: All chiral centers have the same spatial configuration.
- **Syndiotactic Polymers**: Every other chiral center has the same spatial configuration.
- **Atactic Polymers**: Chiral centers have a random spatial arrangement.

2. **Identifying the Monomer**:
- The question suggests examining monomers that can exhibit these three forms.
- A common monomer that can polymerize into all three forms is **propene (CH2=CH-CH3)**.

3. **Analyzing Propene**:
- Propene can undergo polymerization to form polypropylene.
- The structure of propene is:
- CH2=CH-CH3
- When polymerized, the arrangement of the substituents around the double bond can lead to different configurations.

4. **Polymerization Mechanism**:
- During polymerization, propene can link together in various orientations:
- **Isotactic**: All methyl groups (CH3) are on the same side.
- **Syndiotactic**: The methyl groups alternate sides.
- **Atactic**: The methyl groups are randomly oriented.

5. **Conclusion**:
- Since propene can form isotactic, syndiotactic, and atactic polymers, it is the correct answer to the question.

### Final Answer:
The monomer that can polymerize in isotactic, syndiotactic, and atactic forms is **propene (CH2=CH-CH3)**.