Scheme 3. Different Approaches Toward (Poly)(β-peptoid)s that Have Been Described in Literature a a Reprinted with permission from ref 39.

A known limitation of polymer micelles for the formulation of hydrophobic drugs is their low loading capacity (LC), which rarely exceeds 20 wt%. One general strategy to overcome this limitation is to increase the amphiphilic contrast, that is, to make the hydrophobic core of the micelles more hydrophobic. However, in the case of poly(2-oxazoline) (POx)-based amphiphilic triblock copolymers, a minimal amphiphilic contrast was reported to be beneficial. Here, this subject is revisited in more detail using long hydrophobic side chains that are either linear (nonyl) or branched (3-ethylheptyl). Two different backbones within the hydrophobic block are investigated, in particular POx and poly(2-oxazine) (POzi), for the solubilization and co-solubilization of the two highly water insoluble compounds, curcumin and paclitaxel. Even though high loading capacities can be achieved for curcumin using POzi-based triblock copolymers, the solubilization capacity of all investigated polymers with longer side chains is significantly lower compared to POx and poly(2-oxazine)s with shorter side chains. Although the even lower LC for paclitaxel can be somehow improved by co-formulating curcumin, this study corroborates that in the case of POx and POzi-based polymer micelles, an increased amphiphilic contrast leads to less drug solubilization.

The nucleophilic living ring-opening polymerization of N-substituted glycine N-carboxyanhydrides using solid-phase synthesis resins is reported. By variation of experimental parameters, products with near Poisson distributions are obtained. As opposed to reversible deactivation radical polymerization, the living polymerization is demonstrated to be viable to high monomer conversion and through multiple monomer addition steps. Successful preparation of a multiblock copolypeptoid is proof for a highly living and robust character of the solid-phase peptoid polymerization.

The highly modular Ugi four-component reaction (Ugi-4CR) was used to directly obtain polymers of high molar mass bearing aromatic residues in the backbone. By using at least two bifunctional monomers, the Ugi-4CR can be employed to synthesize polymers through a polycondensation under mild conditions in the absence of catalysts. This highly versatile approach allows the creation of vast libraries of molecules by a comparably small pool of compounds. We investigated the six different possible types of the Ugi fourcomponent polymerization (Ugi-4CP) to generate polyamides using commercially available monomers without further purification. After substantial adjustments of reaction parameters, we were able to obtain a polymer of high molar mass, albeit only for one out of the six types of the Ugi-4CP.

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