Reversible Radical Ring-Crossover Polymerization of an Alkoxyamine-Containing Dynamic Covalent Macrocycle

The synthesis of a macrocycle with alkoxyamine-based dynamic covalent bonds and its dynamic polymerization behavior are described. The macrocyclic alkoxyamine was synthesized by condensation of an alkoxyamine-based diol with adipoyl chloride under high-dilution conditions. Spectroscopic measurements revealed that one of the obtained macrocyclic compounds was a [2 + 2] adduct. The [2 + 2] macrocyclic compound acted as a monomer for “ring-crossover” polymerization to afford the corresponding polymer with M n = 2000−18 000 due to the intermolecular radical crossover reaction. The polymerization behavior strongly depended on concentration, time, and temperature. Furthermore, under high-dilution conditions, the obtained poly(alkoxyamine) depolymerized to the monomer or oligomers mainly by the intramolecular radical exchange process.