Chapter 26, Problem 26.39P

Interpretation Introduction

Interpretation:

$\text{N-Vinylcarbazole}$ undergoes cationic polymerization to produce $\text{poly(N-vinylcarbazole)}$, or PVK, which is a photoconducting material used in laser printers. It is to be explained why the monomer readily undergoes cationic polymerization.

Concept introduction:

In any free radical polymerization reaction generally, three steps are involved viz. initiation, propagation, and termination. In the initiation step, free radicals are generated from either monomer or from another compound such as hydrogen peroxide or benzoyl peroxide called a radical initiator instead of radical cations and anions also used for this purpose. In propagation, step radicals react with the monomer to grow the chain to build up polymer and this process is called a chain-growth polymerization or addition polymerization. If the polymerization reaction is initiated by cation, then it called cationic polymerization and when the anion is used, it called anionic polymerization. Generally, the vinyl monomer will undergo anionic polymerization when the electron-withdrawing group(s) are attached to the $\text{C=C}$ bond and it will undergo cationic polymerization when the electron-donating group(s) are attached to the $\text{C=C}$ bond. The addition (cationic or anionic) which forms more stable species will undergo that type of polymerization readily.