Journal article

Efficient polymer passivation of ligand-stripped nanocrystal surfaces

Water-dispersible, polymer-wrapped nanocrystals are highly sought after for use in biol. and chem., from nanomedicine to catalysis. The hydrophobicity of their native ligand shell, however, is a significant barrier to their aq. transfer as single particles. Ligand exchange with hydrophilic small mols. or, alternatively, wrapping over native ligands with amphiphilic polymers is widely employed for aq. transfer; however, purifn. can be quite cumbersome. We report here a general two-step method whereby reactive stripping of native ligands is first carried out using trialkyloxonium salts to reveal a bare nanocrystal surface. This is followed by chem. directed immobilization of a hydrophilic polymer coating. Polyacrylic acids, with side-chain grafts or functional end groups, were found to be extremely versatile in this regard. The resulting polymer-wrapped nanocrystal dispersions retained much of the compact size of their bare nanocrystal precursors, highlighting the unique role of monomer side-chain functionality to serve as effective, conformal ligation motifs. As such, they are well poised for applications where tailored chem. functionality at the nanocrystal's periphery or improved access to their surfaces is desirable. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.


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