Thermo-responsive nanogels based on poly[NIPAAm-gra/f-(2-alkyl-2-oxazoline) ]s crosslinked in the micellar state

Graft copolymers with thermo-sensitive PNIPAAm backbone and hydrophilic PEtOxa graft chains demonstrated typical amphiphilic behavior. For specific compositions stable micellelike aggregates were formed depending on the temperature. Applying long polyoxazoline side chains (DP > 120), stable reversible micelle-like aggregates with hydrodynamic radii of 30-40 nm could be obtained between 33 and 55 °C. These graft copolymers have been successfully crosslinked by electron-beam irradiation in the = micellar state yielding core/shell type nanogels with thermo-reversible swelling behavior. The temperature dependent volume change of the new thermo-responsive nanogels due to the phase transition of the PNIPAAm core has been verified by DLS.