Synthesis of Living Cationic Poly(N-vinylcarbazole) with Low Molecular Weight

Abstract

Living cationic polymers of N-vinylcarbazole (NVC) with controlled low molecular weight (Mn=103–104) and narrow molecular weight distribution (Mw/Mn∼1.2) were synthesized with iodine initiator at −78°C in methylene chloride containing a common-ion salt (nBu4NI). The polymerization was carried out at low NVC concentration (20—60 mM; [I2]0=1.0 mM; [nBu4NI]=0.50 mM) by the successive addition of small amounts of the monomer to a completely polymerized solution. At each stage of the monomer addition, the reaction was rapid and quantitative (completed within 5 min), and the number-average molecular weight (Mn) of the polymers was proportional to the total amount of added NVC. In salt-free methylene chloride solvent, on the other hand, such living polymerization did not take place; the Mn of the total polymer decreased with further monomer addition. At higher temperatures (−30 and −15°C), no living polymers were obtained even in the presence of the added salt.