Cationic Polymerization Alkene is treated with an acid. Intermediate must be a stable carbocation. Initiation steps:The catalyst protonates the monomer,starting the chain. H CH, CH B*+HO: +F一B一OE CH. CH H isobutylene initiated chain Copyright 2005 Pearson Prentice Hall,Inc. Propagation step:Another molecule of monomer adds to the chain. tertiary carbocation CH CH CH CH CH H CH,H CH. growing chain isobutylene elongated chain polymer Copyright 2005 Pearson Prentice Hall,Inc. 三>Chapter 26 7 Cationic Polymerization • Alkene is treated with an acid. • Intermediate must be a stable carbocation. =>