PSar is most commonly prepared via nucleophilic living ring-opening polymerization (NuLROP) of N-substituted α-amino acid-N-carboxyanhydrides (NNCAs) , which can be initiated with a variety of nucleophiles. Most commonly, amines are employed , but water , alcohol , thiols and others have been reported. Notably, PSar and other polypeptoids can also be obtained by NuLROP from the more stable N-substituted αamino acid-N-thiocarboxyanhydrides (NNTAs) . Apart from determining the polymer chain length via [M]0/[I]0, an initiator can be chosen to introduce specific functional groups in the α-terminus of the polymers. However, it is important to consider that the introduced functionalities must be compatible with the polymerization process. Only a few papers introduced functional initiators for NCAs polymerization. Tao et al. reported on ROP of Nsubstituted glycine N-thiocarboxyanhydride with cysteamine with a further application for thiolene and thiol-yne click chemistry . Later, Johann and co-workers introduced the aminofunctional trans-cyclooctenes (TCO) and 6-methyl-tetrazine (mTz) as initiators to obtain functional polypeptoids and performed their post-polymerization modification . Postpolymerization modification (PPM) can help to overcome limitations that occur during polymerization and introduce responsive, structural and functional properties into polymers, which are otherwise incompatible with the polymerization process . PPM can offer several advantages. On one hand, a variety of different functionalities can be introduced into the side chain or termini of a polymer. On the other hand, the resulting polymer will have the same degree of polymerization and chain length distribution as the original polymer. PPM also allows the synthesis of polymers with functionalities that can not or only inconveniently be introduced directly via the polymerization.