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Chemistry Project

Gegen Ion Pairs

Butyl rubber gloves

Outline

Monomers

Olefins

• Presence of an electron-donating group
• Example: isobutylene

Heterocyclic monomers

• Ring strain
• Examples: lactones, lactams, cyclic amines, and cyclic ethers

Solvents

• Gegen ion effects
• Polar versus nonpolar solvents

Synthesis

Initiation

Classical protonic acids/acid surfaces

• Nucleophilicity of the anion

• Examples: perchloric, sulfuric, and phosphoric acids

Lewis acids/Friedel-Crafts catalysts

• Examples of Lewis acids: metal halides and their organometallic derivatives
• Cocatalyst for Lewis acids

• Examples: water, hydrogen halides, and alcohols

Carbenium ion salts

• Direct addition
• Hydride extraction
• Electron transfer

Propagation

• Counterion effect on rate of propagation

• Counterion position in reaction

Figure X. Gegen Ion Position

• Useful temperature (170-190 K)

Termination

Unimolecular rearrangement

• Catalyst-cocatalyst complex regenerated
• Termination of the kinetic chain

Bimolecular transfer reactions

• Monomer-initiator complex regenerated
• No termination of the kinetic chain

Living Polymerization

• Link to living cationic polymerization Wiki page: Living cationic polymerization

Kinetics

• Steady-state conditions

Commercial Applications

• Examples: tackifiers, adhesives, sealants, moisture barriers, tubing