Poly(thio)ester amides (PEAs and PTEAs) represent an important class of functional polymers, uniquely integrating the exceptional degradability of poly(thio)esters with the superior mechanical properties of polyamides. Ring-opening copolymerization (ROCOP) of aziridine and cyclic (thio)anhydride stands out as a highly efficient method for constructing alternating PEAs and PTEAs; however, existing ROCOP systems largely rely on N-alkyl or N-sulfonyl aziridines, which precludes interchain hydrogen bonding. Here, we report a protected–deprotected strategy based on N-tert-butyloxycarbonyl aziridine (AzBoc) as a N–H aziridine precursor, enabling the postpolymerization deprotection to restore the amide N–H groups and introduce hydrogen-bonding interactions. Efficient ROCOP of AzBoc with various cyclic (thio)anhydrides, such as phthalic thioanhydride (PTA), phthalic anhydride (PA), diphenic anhydride (DPA), and camphoric anhydride (CA), was achieved using either organic bases (e.g., phosphazene) or nucleophilic salts (e.g., tetrabutyl ammonium chloride), affording cyclic PEAs and PTEAs with well-defined alternating structures and high molar masses. Structure–property relationship studies demonstrate that Boc deprotection, sulfur atom incorporation, and anhydride ring size collectively govern the thermal properties of the resulting polymers, underscoring the critical role of amide hydrogen bonding in modulating material performance.
Qin et al. (Tue,) studied this question.