Nanoparticle synthesis via bubbling vapor precursors in bulk liquids
Conventional methods for preparing polymer nanoparticles and organic–inorganic composite nanoparticles use solution based top-down processes with surfactants and mechanical stirring. Examples of such processes include emulsion polymerization of monomers to produce polymer nanoparticles and sol–gel reactions involving hydrolysis of inorganic precursors to produce inorganic materials (such as silica and titanium nanoparticles). Here, we show that vaporized precursors of various compounds can be used as reactants to produce polymer, inorganic, and composite nanoparticles. The bubbling action of precursor vapor in a reactant vessel provides a constant supply of precursor species while aiding their rapid mixing in the bulk solution liquid. The vaporization and bubbling processes require only small amounts of energy to prepare nanoparticles or core–shell nanoparticles without forming unwanted side products. Compared to other available techniques, this approach enables precise control of nanoparticle size and shell thickness as functions of vapor supply time and temperature without surfactants. Our approach can potentially be applied to fabricate functional nanomaterials using organic and inorganic precursors for medical, electrical, optical, magnetic and/or catalytic applications.