title: Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.
abstract: Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853.
authors.forename: Zihui
authors.initials: Z
authors.lastname: Li
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sai
authors.forename: Scott C
authors.initials: SC
authors.lastname: Warren
authors.forename: Marleen
authors.initials: M
authors.lastname: Kamperman
authors.forename: Hitesh
authors.initials: H
authors.lastname: Arora
authors.forename: Sol M
authors.initials: SM
authors.lastname: Gruner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wiesner