Ultrastable suspensions of polyoxazoline-functionalized ZnO single nanocrystals

The synthesis and characterization of poly-2-methyl-2-oxazoline-stabilized ZnO single nanocrystals (PMOXA:ZnO NCs) featuring ultrastable suspensions are presented in this report. The inorganic NCs are first synthesized by the inverse w/o miniemulsion (ME) process in the presence of polymeric surfactants which are subsequently exchanged by PMOXA ligands with nitrodopamine (ND) anchors as chain ends. Interplay between ligand relative concentration and chain length allowed the preparation of PMOXA-stabilized suspensions of single NCs presenting a platelet-like morphology and a uniform polymer coating. The strong binding of ND-derivatized anchors to the metal oxide surfaces together with the high stability of PMOXA against chemical oxidation enable the formation of suspensions presenting excellent colloidal stability over very long incubation times in aqueous media (up to 9 months). The combination of the ME approach with engineered PMOXA-ND functionalities thus proved to be a highly efficient technique to design novel polymer/inorganic colloidal systems with enhanced stability for potential bioimaging applications.