title: Mechanisms of Polymer-Templated Nanoparticle Synthesis: Contrasting ZnS and Au.
abstract: We combine solution small-angle X-ray scattering (SAXS) and high-resolution analytical transmission electron microscopy (ATEM) to gain a full mechanistic understanding of substructure formation in nanoparticles templated by block copolymer reverse micelles, specifically poly(styrene)-block-poly(2-vinylpyridine). We report a novel substructure for micelle-templated ZnS nanoparticles, in which small crystallites (∼4 nm) exist within a larger (∼20 nm) amorphous organic-inorganic hybrid matrix. The formation of this complex structure is explained via SAXS measurements that characterize in situ for the first time the intermediate state of the metal-loaded micelle core: Zn(2+) ions are distributed throughout the micelle core, which solidifies as a unit on sulfidation. The nanoparticle size is thus determined by the radius of the metal-loaded core, rather than the quantity of available metal ions. This mechanism leads to particle size counterintuitively decreasing with increasing metal content, based on the modified interactions of the metal-complexed monomers in direct contrast to gold nanoparticles templated by the same polymer.
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Lucia
authors.initials: L
authors.lastname: Podhorska
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Derfogail
authors.initials: D
authors.lastname: Delcassian
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Angela E
authors.initials: AE
authors.lastname: Goode
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Agyei
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.|Department of Materials Science and Engineering and Center for Electron Microscopy and Analysis, Ohio State University , 1305 Kinnear Road, Columbus, Ohio 43212, United States.
authors.forename: David W
authors.initials: DW
authors.lastname: McComb
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Mary P
authors.initials: MP
authors.lastname: Ryan
authors.affiliation: Department of Materials, Imperial College London , Prince Consort Road, London, SW7 2AZ, United Kingdom.
authors.forename: Iain E
authors.initials: IE
authors.lastname: Dunlop