IONIC POLYMERIZATION

What type of intermediate is formed during cationic polymerization?

• Carbanion

• Radical

• Carbocation

• Anion

Which step characterizes the initiation process in both anionic and cationic polymerization?

• Coupling of two polymer chains

• Formation of a carbocation or carbanion

• Termination of the polymer chain

• Addition of a monomer to a growing chain

Which of the following serves as an effective initiator (catalyst) in cationic polymerization?

• Strong protonic acids (e.g., HCl, H₂SO₄, HClO₄)

• Strong reducing agents (e.g., LiAlH₄)

• Strong bases (e.g., NaOH, KOH)

• Strong oxidizing agents (e.g., KMnO₄)

How does propagation differ between anionic polymerization and cationic polymerization?

• In anionic polymerization, the propagation involves the reaction of a carbocation with a monomer, while in cationic polymerization, it involves a carbanion with a monomer.

• In anionic polymerization, the propagation occurs through the addition of a monomer to a growing chain, while in cationic polymerization, it involves the reaction of a carbocation with a monomer.

• In anionic polymerization, the propagation is initiated by the addition of a neutral nucleophile to a monomer, while in cationic polymerization, it is initiated by a strong electrophile.

• In anionic polymerization, the propagation step regenerates the anionic chain end with each monomer addition, while in cationic polymerization, it creates a new carbocation at the chain end.

Which factors significantly influence the rate and molecular weight control in anionic polymerization reactions?

• Catalyst type, solvent polarity, and reaction time

• Temperature, monomer concentration, and initiator concentration

• pH of the reaction medium, chain transfer agents, and reaction pressure

• Monomer structure, stirring speed, and atmospheric conditions

Which method of initiation is described in the context of anionic polymerization of styrene involving butyllithium (Bu-Li+)?

• Formation of a radical anion by electron transfer

• Direct electron transfer from alkali metal to monomer

• Nucleophilic addition to the monomer's double bond

• Anionic addition polymerization induced by electronegative groups

Who demonstrated "live polymerization" in 1956, showcasing continuous addition of styrene using electron transfer from sodium naphthalene radical anion?

• Karl Ziegler

• Michael Szwarc

• Stavely

• Roderic Quirk

Which step is crucial for initiating cationic polymerization?

• Formation of a stable carbanion

• Addition of a nucleophile to the monomer

• Interaction with an electrophile to form a carbocation

• Introduction of a radical initiator

What is a similarity in the termination process between cationic polymerization and anionic polymerization?

• Both involve the combination of two active chain ends to terminate polymer growth.

• Both rely on the reaction of a carbocation with a neutral nucleophile to terminate the chain.

• Both require the transfer of a carbocation to a monomer to terminate polymerization.

• Both terminate by disproportionation between polymer chains.

What is the function of the monomer in cationic polymerization?

• It acts as a catalyst to initiate the polymerization process.

• It provides the repeating units that form the polymer chain.

• It stabilizes the carbocation formed during polymerization.

• It terminates the polymerization reaction by neutralizing the initiator.