Sustainable bio based poly N glycines and polyesters Nowadays the need to protect the environment becomes more urgent than ever. In the field of chemistry this translates to practices such as waste prevention use of renewable feedstocks and catalysis; concepts based on the principles of green chemistry. Polymers are an important product in the chemical industry and are also in the focus of these changes. In this thesis more sustainable approaches to make two classes of polymers polypeptoids and polyesters are described. Polypeptoids or poly(alkyl N glycines) are isomers of polypeptides and are biocompatible as well as degradable under biologically relevant conditions. In addition to that they can have interesting properties such as lower critical solution temperature (LCST) behavior. They are usually synthesized by the ring opening polymerization (ROP) of N carboxy anhydrides (NCAs) which are produced with the use of toxic compounds (e.g. phosgene) and which are highly sensitive to humidity. In order to avoid the direct synthesis and isolation of the NCAs ...