Cyclic poly(vinylcarbazole) via ring-expansion polymerization-RAFT (REP-RAFT)

In this paper, we demonstrate the formation of cyclic poly(vinylcarbazole) via a ring-expansion polymerization reversible addition-fragmentation chain transfer (REP-RAFT). A cyclic dixanthate RAFT chain transfer agent (CTA) was synthesized and employed for controlled free radical polymerization of N-vinylcarbazole (NVK). The molecular weight in relation to polymerization time suggested the formation of a polymer with well-controlled molecular weight and ring size. The obtained macromolecules were characterized by nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS). Atomic force microscopy (AFM) was also employed to directly observe the cyclic polymers with different ring sizes.