Promising new active pharmaceutical ingredients (API) are discovered in pharmaceutical industry and academia on a daily basis, but one major challenge remains the formulation of the API. According to estimates, 40% -60% of all new drugs are practically in-soluble in water. Therefore, a plethora of methods is used to increase their solubility. Polymer micelles are nanoscopic structures formed by amphiphilic (block) copolymers. In a simplified picture, hydrophobic APIs are dissolved in the hydrophobic core, whereas the hydrophilic shell acts as a protective layer to prevent premature disintegration or unwanted protein interactions and to ensure a sufficient water solubility. However, the actual situation may be more complex as recently shown for a variety of drug loaded micelles, as the nature of the hydrophobic block can significantly affect the drug loading. [5, 6] A particularly strong effect was reported for the different solubilization behaviors of structurally very similar poly(2-oxazoline) (POx) and poly(2-oxazine) (POzi) based drug delivery vehicles (Scheme 1). Small structural changes in the polymer sidechain and polymer backbone of the hydrophobic core caused pronounced differences in the solubilization capacity for different hydrophobic compounds such as curcumin (CUR) and paclitaxel (PTX). The investigated formulations are of particular interest as extremely high CUR-loading > 50 wt.% were observed, which is highly unusual for drug-loaded micelles, since they generally suffer, with notable exceptions [14, 15] , from rather low drug-loadings < 20 wt.%.