Investigations on segmented polymer networks and protein conjugates based on end-group functionalized poly(2-oxazoline)s

The specific design of defined macromolecular components enables the formation of diverse nanostructured materials with tailored properties. In this work, different poly(2-oxazoline)s (POx) with functional terminal double bonds were synthesized and characterized both for the design of segmented polymer networks (SPNs) and for the conjugation of proteins. In the first section, two novel families of amphiphilic polymer copolymer networks (APCNs) were prepared by copolymerizing hydrophobic poly(2-(1-ethylpentyl)-2-oxazoline) functionalized on both sides with one of the hydrophilic monomers 2-hydroxyethyl acrylate (HEA) or N,N-dimethylacrylamide (DMA) while varying the composition. The network syntheses were carried out via the macromeric cross-linker approach using a defined, telechelic polymer with a high degree of functionalization to achieve ordered structures in the networks through a component that is as highly defined as possible. All synthesized APCNs were swollen in the solvents water, toluene, or n-heptane and the intrinsic nanophases of the materials were investigated by small angle X-ray scattering (SAXS) both in the dry and in the swollen state. The HEA-based APCNs in particular showed ideal nanostructural swelling properties, since swelling in the phase-selective solvents water or n-heptane leads to swelling of the respective addressed polymer phase, whereby it was shown that the nanostructural order is retained. Furthermore, SPNs based on the hydrophilic polymer components polyethylene glycol (PEG) with either poly(2-methyl-2-oxazoline) or poly(2-ethyl-2-oxazoline) were prepared in the following section by cross-linking the bifunctional acrylate end-groups. The obtained SPNs were characterized by SAXS in the dry and swollen state with respect to their nanostructure. Depending on their composition, a SPN system was identified with no initial nanostructure, but in which a clear phase separation could be induced by the influence of elevated temperature or selective solvent. Furthermore, in a comparative study, polymer-protein conjugates via Michael addition reactions between terminally acrylate-functionalized PEG or POx with varying chain lengths and the proteinogenic amino groups of lysozyme as a model protein were investigated. The respective conjugation efficiency was analyzed by SDS-PAGE and the reactivities of the respective polymeric acrylate end-groups were further characterized by 1H-NMR spectroscopy.