The cationic polymerization mechanism involves initiation, propagation, and termination steps.
In the initiation step, the Lewis acid catalyst, formed from boron trifluoride and water, protonates the π bond of a monomer, generating a carbocation stabilized by the electron‐donating group.
In the propagation step, the generated carbocation is attacked by the π bond of a second monomer, forming a dimer that acts as a new carbocation.
The propagation step repeats itself and enables the polymer chain to grow.
In the termination step, the growing polymer chain is terminated by adding a base that deprotonates the carbocation, forming a new π bond.
Alternatively, a nucleophile that attacks the carbocation could also be used.
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation, thereby producing a dimer that acts as a new carbocation. The propagation step repeats itself and builds the polymer chain. In the termination step, the propagating chain gets terminated either by adding a base that deprotonates the carbocation and forms a new π bond or by the attack of a nucleophile on the carbocation, where the nucleophile adds to the cationic end of the chain.