Self-Limited Hyperbranching Polymerization of Di-N-Phenoxycarbonyl N-Substituted Diglycines

Hyperbranched poly(a-amino acid)s have caught great attention due to their excellent biocompatibility, biodegradability, and bioactivity. However, hyperbranched polypeptoids are rarely reported because of the challenge of synthesis. Herein, unique polymerizations of N,N'-diphenoxycarbonyl-N,N'-(1,4-phenylenebismethylene)-diglycine (di-NNPC, an A*B*-A*B*-type monomer) which uncommonly result in hyperbranched polypeptoids rather than gels after the complete consumption of di-NNPC are reported. The molecular weights of the hyperbranched polypeptoids are controlled by the degree of branching via tuning the initial concentrations of monomer and basic catalyst. N-Phenyloxycarbonyl glycine pendant groups plentifully remained on the polymer chains are used for Gd3+ complexation and post-modification, which makes the hyperbranched polypeptoids multifunctional single molecular micelles applicable as magnetic resonance imaging contrast agents and photoluminescence probes.