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Microemulsions as Templates for New Materials Project I: Metallic Nanoparticles

Microemulsions as Templates for New Materials Project I: Metallic Nanoparticles Project II: High Surface Area Polymers. Dr. Cosima Stubenrauch School of Chemical and Bioprocess Engineering, UCD, Ireland Dublin, 27 th September 2007.

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Microemulsions as Templates for New Materials Project I: Metallic Nanoparticles

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  1. Microemulsions as Templates for New Materials Project I: Metallic Nanoparticles Project II: High Surface Area Polymers Dr. Cosima Stubenrauch School of Chemical and Bioprocess Engineering, UCD, Ireland Dublin, 27th September 2007

  2. surfactant concentration < 1 % surfactant concentration > 10 %  thermodynamically stable  thermodynamically unstable What is a Microemulsion? emulsion „microemulsion“ H2O H2O oil oil ~ 5 nm  ~ 5 µm J.H. Schulman, W. Stoeckenius, L.M. Prince, J. Chem. Phys., 1959,63, 1677

  3. x • o/w-µe • ~ 5 nm A ~ 60 - 240 m2/g • bicontinuous µe • ~ 10 - 50 nm A ~ 150 - 30 m2/g • w/o-µe • ~ 5 nm A ~ 60 - 240 m2/g Structures of Microemulsions x Goal: High Surface Area Material with Surface/Volume Ratio as large as possible via Templated Synthesis!

  4. Project I: Metallic Nanoparticles Dr. Cosima Stubenrauch, Dr. Reza Najjar, Miguel Magno School of Chemical and Bioprocess Engineering, UCD, Ireland Prof. Frank DiSalvo Department of Chemistry, Cornell University, Ithaca, NY Prof. Vincenzo Turco Liveri, Dr. Cristina Giordano University of Palermo, Italy Dr. Thomas Sottmann, Prof. Reinhard Strey Institut für Physikalische Chemie, Universität zu Köln, Germany

  5. Pt Pt initial droplet size ~ final nanoparticle size Project I: Metallic Nanoparticles - Concept oil + surfactant + aqueous phase 1 2 (2) H2PtCl6 (1) NaBH4 ~ 5 nm ~ 5 nm w/o-µe w/o-µe 1 2 t (exchange of reactants)  t (fusion-fission) Capek, Adv. Colloid Interface Sci., 2004, 110, 49; Uskokovic, Surf. Rev. Lett., 2005 , 12, 239.

  6. Strategy (1) add reducing agent (NaBH4) to base system and remeasure wefb (2) add metal precursor (e.g. H2PtCl6) to base system and remeasure wefb Project I: Metallic Nanoparticles - Concept wefb = water emulsification failure boundary = droplet formation C. Stubenrauch, T. Wielpütz, T. Sottmann, C. Roychowdhury, F. J. DiSalvo, COLSUA, submitted

  7. oil + surfactant + aqueous phase 1 2 (1) NaBH4 (2) H2PtCl6 + Bi(NO3)3 or ~ 5 nm ~ 5 nm + Pb(NO3)2 (2) H2PtCl6 w/o-µe w/o-µe Bi/Pt Bi/Pt initial droplet size ~ final nanoparticle size Project I: Metallic Nanoparticles - Goal Intermetallic Pt/Bi and Pt/Pb Nanoparticles for Fuel Cells • Challenges • time-consuming studies of phase diagrams • large difference in reduction potentials: [PtCl6]2-/[PtCl4]2- = +0.68V, • [PtCl4]2-/Pt = +0.76V, Bi3+/Bi = +0.22 V Pb2+/Pb = -0.13 V • reaction of NaBH4 with H2O DiSalvo et al., J. Electr. Soc.2004, 151, A971

  8. Project I: Metallic Nanoparticles - Results Compositions of microemulsions containing metal precursor and reducing agent; all microemulsions were titrated with 1-butanol to determine the webf; gb = 0.05, wA = 0.05, T = 21°C R. Najjar, C. Stubenrauch, JCIS, manuscript in preparation

  9. Intensity / a.u. 90 10 30 40 60 70 80 50 20 2  / ° R. Najjar, C. Stubenrauch, C. Giordano, V. Turco Liveri, preliminary results Project I: Metallic Nanoparticles - Results bismuth 20 – 30 ° Glass Substrate 20 – 30 ° Glass Substrate C. Stubenrauch, T. Wielpütz, T. Sottmann, C. Roychowdhury, F. J. DiSalvo, COLSUA, submitted

  10. Project I: Metallic Nanoparticles - Techniques • Phase Diagrams of Microemulsions • 3 water basins and 1 cryostat; available group Dr. Stubenrauch • Characterization of Metallic Nanoparticles • UV/VIS – completeness of reduction; available group Dr. Stubenrauch • XRD (X-ray diffraction) or WAXS (wide angle X-ray scattering) – • composition; available groups Dr. Carr, Dr. Dowling but currently • “out of order” • SAXS (small angle X-ray scattering) – size, size distribution and • shape; SFI equipment call Dr. C. Stubenrauch 344,400 € • Scanning Electron Microscope – size and shape; • SFI equipment call Prof. D. MacElroy1,325,998 €

  11. Project II: High Surface Area Polymers Dr. Cosima Stubenrauch, Miguel Magno School of Chemical and Bioprocess Engineering, UCD, Ireland Dr. Iseult Lynch, Dr. Anna Salvati, Prof. Kenneth Dawson School of Chemistry and Chemical Biology, UCD, Ireland Renate Tessendorf, Dr. Thomas Sottmann, Prof. Reinhard Strey Institut für Physikalische Chemie, Universität zu Köln, Germany

  12. Project II: High Surface Area Polymers - Concept AIM porous polymer with A ~ 150 - 30 m2/g x RESULT porous polymer with A ~ 3 - 0.6 m2/g REASON tstructural changes << tpolymerisation SOLUTION slow down / arrest structural changes bicontinuous µe A ~ 150 - 30 m2/g Raj et al. Polymer 1995, 36, 2637 Henzte et al. Top. Curr. Chem. 2003, 226, 197 IT IS ALL A MATTER OF TIMESCALES!

  13. H2O – n-dodecane – C13/15E5 water (oil) oil (water) arrest replace 1 2 polymerisable aqueous (oil) phase organogel (hydrogel) remove polymerise 3 4 a = 0.5 water- (oil-) soluble high surface area polymer Project II: High Surface Area Polymers - Concept Remeasure Phase Diagram after each compositional change! Stubenrauch, C., Tessendorf, R., Strey, R., L., Lynch, I., Dawson, K.A., Langmuir, 2007, 23, 7730

  14. (1) High Surface Area p-NIPAm = Stimuli-Responsive Hydrogel pharmazeutical applications: control of release rate for drug delivery (high surface area = small pore size = fast response) biomimetic material: functionalize the polymer with biologically active entities (2) Conjugated Polymers for PV Cells (SRC) „continuous“ polymer = electron donator top electrode „continuous“ TiO2 = electron acceptor transparent electrode Coakley et al. Chem. Mater. 2004, 16, 4533. Project II: High Surface Area Polymers – Goals Lynch, I., Dawson, K. A., Macromol. Chem. Phys. 2003, 204, 443 and references therein.

  15. 1. Base Microemulsion H2O – n-dodecane – C13/15E5 2. Polymerisable Aqueous Phase N,N’-methylene bisacrylamide, BisAm, Crosslinker N-isopropylacrylamide, NIPAm, Monomer 3. Organogel 12-HOA – n-dodecane Project II: High Surface Area Polymers – Results x bicontinuous µe A ~ 150 - 30 m2/g Stubenrauch, Tessendorf, Strey, Lynch, Dawson, Langmuir, 2007, 23, 7730

  16. a = 0.5 y = 0.07 Project II: High Surface Area Polymers – Results H2O/NIPAM – n-dodecane/12-HOA – C13/15E5 1. Gelled Microemulsion! 2. Bicontinuous Structure! 3. Domain Size Template? 4. Polymerisation? 5. Domain Size Polymer? TEM, SANS polymerize NMR Stubenrauch, C., Tessendorf, R., Strey, R., Lynch, I., Dawson, K.A., Langmuir, 2007, 23, 7730 Stubenrauch, C., Tessendorf, R., Strey, R., Belkoura, L.,Lynch, I., Salvati, A., Dawson, K.A., Langmuir, in preparation

  17. Project II: High Surface Area Polymers - Techniques • Phase Diagrams of Microemulsions • 3 water basins and 1 cryostat; available group Dr. Stubenrauch • Polarization Microscope with camera and hotstage; available group • Dr. Stubenrauch • Characterization of Template (T) / High Surface Area Polymer (P) • Conductivities – bicontinuity of T; available group Dr. Stubenrauch • Surface Area and Pore Size Analyser; available group Prof. MacElroy • DOSY NMR – bicontinuity of T / P; available at UCD • SAXS (small angle X-ray scattering) – domain size and structure of T / P; • SFI equipment call Dr. C. Stubenrauch344,400 € • High Resolution Transmission Electron Microscope with Freeze Fracture • and Freeze Etch System– domain size and structure of T / P

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