Materials for nano -composite films

1. E(z)/kT Nanoparticle Assembly Oil phase Water A OH H2O interior H2O OH HO Oil Emin 20µm Toluene/CdSe z/R C 80 mm 20 mm 100 nm TCB 50 nm Water Responsive Nanocomposites: using ligands to direct nanoparticles to polymer domains and interfacial boundaries Idealized schematic of responsive nanocomposite Thermal annealing Effect on mechanical properties?? Interfacial energy well: Droplet resizing through track-etch membranes Confocal images reduction in droplet size from 200 mm to 10 mm and less 25% OH terminated: NPs segregate to PS-PVP interface 50% OH terminated: NPs distributed within PVP domain 170 deg C Nanoparticle ripening + entropic penalty = reorganization Diblock copolymer host: polystyrene-poly(4-vinylpyridine) avg. 4.5 nm diameter Au NPs Lamellar morphology (solvent annealed films) with avg. 2.4 nm Au NPs NIRT: Controlling Interfacial Activity of Nanoparticles: Robust Routes to Nanoparticle-based Capsules, Membranes, and Electronic Materials (CBET 0609107) Todd Emrick and Thomas P Russell, Polymer Science & Engineering Department, University of Massachusetts Amherst Anthony Dinsmore and Narayanan Menon, Physics Department, University of Massachusetts Amherst Benny D. Freeman, Chemical Engineering Department, University of Texas at Austin B Objectives: Harness the interfacial activity of nanoparticles, and the reactivity of functionalized ligands, for the preparation of robust, self-assembled structures , devices, and membranes Interfacial assembly of nanoparticles: droplets and sheets Pieranski, P. Phys. Rev. Lett 45, 569 (1980) TOPO-covered CdSe quantum dots Fluorescence confocal images of quantum dots on water droplets in a continuous oil phase Lin, Y., Skaff, H., Emrick, T., Dinsmore, A. D. & Russell, T. P., Science 299, 226-229. Film Formation at the Interface D 1 mm 4.6 nm CdSe in Toluene/Water H. Zettl, Universität Bayreuth Self-assembled nanorods and bionanorods using fluid interfaces The structure and orientation of nanorods at the liquid-liquid interface can be manipulated by varying nanorod concentration in the bulk. At low TMV concentration, the rods orient parallel to the interface, which maximizes interfacial stabilizaiton. At high TMV concentrations, the rods orient normal to the interface, both mediating the interfacial interactions and neutralizing inter-rod electrostatic repulsion. For charged nanorods like TMV, repulsive forces dominate the oil-water interfaces, which is strongly affected by the ionic strength, but not the pH, of the bulk solution in the range of pH = 6~8. Removal of the buffer solution leads to cleavage of the TMV nanorods at the oil/water interface. Materials for nano-composite films Di-sulfonated poly(arylene ether sulfone) (BPS): BPS-XY series, X = mol% of disulfonated monomer (0<X<100), Y = “H” (free acid form) , “N” (sodium salt form), or “K” (potassium salt form). Acid/base tolerance: steady water permeability and salt rejection over a wide range of pH Au nanoparticles: EG4-058A Citrate-stabilized gold nanoparticles in water ~20 nm in diameter ~1 mg/ml in water • Measured in cross-flow cells. Feed solution: 2000 ppm NaCl, pressure = 27.2 atm (400 psig), flow rate = 1 gpm, temperature = 25oC. • 2. BPS-32K/0.5%Au: BPS-32K with 0.5 wt% of Au nanoparticles (EG4-058A)