Self-assembled structures of poly(2-isopropyl-2-oxazoline) (PiPOx) and poly(L-lactide) (PLLA) block copolymers in water were studied by dynamic light scattering (DLS) and UV-VIS spectroscopy (UV-VIS). The block copolymers were prepared by azide-alkyne cycloaddition between PiPOx and PLLA homopolymers. The homopolymers were prepared via ring-opening polymerization (ROP) techniques. The kinetics of the cationic ROP of PiPOx was investigated. The self-assembled structures were prepared via four different methods: nanoprecipitation, solvent exchange, dialysis, and thin film rehydration. Self-assembled structures prepared from solvent exchange and dialysis had larger hydrodynamic radii than particles prepared from nanoprecipitation, due to a slower change in solvent quality. According to the Rg/Rh values, spherical structures were formed after nanoprecipitation. When the particles were heated to 50 °C, a sphere-to-rod transition took place. Self-assembled structures prepared via solvent exchange exhibited thermo-responsiveness when the PiPOx block was long enough. Surprisingly, the small structures prepared via nanoprecipitation did not show any thermo-responsiveness.
