The best way to prepare polyisobutylene is: (a) Coordination polymerization (b) Free radical polymerization (c) Cationic polymerization (d) Anionic polymerization

Cationic polymerization is a type of chain-growth polymerization where the active center of the chain is a cation, making this process sensitive to the presence of electron-rich monomers and requiring an electron-deficient catalyst, typically a strong acid. Unlike free radical polymerization, which can proceed with various types of monomers, cationic polymerization is ideal for monomers with easily donated electrons.
During cationic polymerization, the monomer forms a bond with the growing polymer chain by transferring its electron pair, thus allowing the cationic species to remain active for chain propagation. This reaction is highly sensitive to the nature of the solvent and can be halted by minute traces of impurities, such as water, which can deactivate the cationic chain carriers.
The selectivity and control offered by cationic polymerization make it a valuable process for creating well-defined polymers, which is beneficial for tailoring materials with specific properties for different applications.

Polyisobutylene (PIB) is a vital industrial polymer known for its stability and resistance to chemicals, making it suitable for use in lubricants, adhesives, and sealants. To prepare high-quality PIB, choosing the correct polymerization process is pivotal.
Polyisobutylene is typically synthesized by cationic polymerization because the isobutylene monomer is particularly suited to this mechanism. In the controlled environment of a cationic polymerization reaction, isobutylene interacts with a strong protonic acid or Lewis acid catalyst to form a carbocationic intermediate. This intermediate then acts as a reactive site for subsequent monomer addition, allowing the polymer chain to grow in a stepwise fashion.
One of the critical aspects of producing PIB is controlling the molecular weight distribution. Cationic polymerization offers a level of control that other methods lack, which is essential in applications requiring PIB with specific molecular weights and consistent properties.

The National Eligibility cum Entrance Test (NEET) is one of the most competitive exams for students aspiring to enter the medical field in India. Chemistry is a vital subject in the NEET curriculum, and understanding concepts like polymerization is essential for success.
Polymerization reactions, particularly cationic polymerization, illustrate the depth of organic chemistry. Comprehending chemical mechanisms, such as how polyisobutylene is formed, provides a strong foundation for more advanced topics. NEET questions often test students' ability to understand and apply these concepts to various scenarios, which is why having a thorough grasp of polymerization is crucial.
In preparing for NEET, students must focus on concept clarity, critical thinking, and the ability to solve problems efficiently. Topics like cationic polymerization and polyisobutylene preparation are relevant not just as isolated facts but as part of a larger understanding of organic chemistry's role in medical applications, such as drug design and development.