Reversible ring-crossover polymerization of macrocycles based on radical exchange reaction

Recently, the authors have reported the synthesis of "dynamic covalent polymers" which have alkoxyamine-based dynamic covalent bonds in their main chains. In this study, the authors report the reversible "ring-crossover" polymerization behavior of macrocycles containing alkoxyamine units which can show radical crossover reaction upon heating. Simple heating of the [2+2] macrocycle in anisole at 398 K afforded the corresponding poly(alkoxyamine) with M_n=2000-18000 due to the intermolecular radical crossover reaction. A [1+1] macrocycle was also synthesized by using diacid chloride with longer spacer. The oligomers obtained by radical ring-crossover polymerization were depolymerized to the monomers mainly by the intramolecular radical exchange process under high-dilution conditions.