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Jan Perlich TU München, Physik-Department LS E13, James-Franck-Str. 1, D-85747 Garching

Nanostructured Films of Selfencapsulating Inorganic-Organic Hybrid Materials DFG-SPP 1181 NANOMAT. Jan Perlich TU München, Physik-Department LS E13, James-Franck-Str. 1, D-85747 Garching. Mine Memesa Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz.

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Jan Perlich TU München, Physik-Department LS E13, James-Franck-Str. 1, D-85747 Garching

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  1. Nanostructured Films of Selfencapsulating Inorganic-Organic Hybrid Materials DFG-SPP 1181 NANOMAT Jan Perlich TU München, Physik-Department LS E13, James-Franck-Str. 1, D-85747 Garching Mine Memesa Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz Prof. Dr. J.S. GutmannSebastian Nett Yajun Cheng PD Dr. P. Müller-Buschbaum

  2. Ultra-thin films Spin coating Calcination Ordered crystallites Basic materials (before SPP1181) Micelles in solution AmphiphilicPS-b-PEO + Sol-gel chemistry Titan(IV)oxid sol-gel precursor Ternary phase diagram Goal: Intelligent, nanostructured materials • Use of functional inorganic materials • TiO2 (crystalline) photocatalysis photovoltaic Y.-J. Cheng, J. S. Gutmann, JACS, 128, 4658 (2006).

  3. Properties of prototype solar cells PHT= regioregular Poly(3-hexylthiophene) Dye = cis-(SCN)2 bis (2,2’ bipyridyl-4,4 -dicarboxylate) ruthenium(II)  PS-b-PEO and PMMA-b-PEO as amphiphilic block-copolymers PMMA-b-PEO (24k/18k) ~ 50nm particles PS-b-PEO (19k/6k)~ 20nm particles

  4. Goal: Integrated self-encapsulation Central problem: Quality of barrier layer Can we improve or replace the blocking layer? • Yes, use different polymer!

  5. How do we test our integrated approach? 1.) Pre-test with „conventional“ nanoparticles • Covering of “conventional” titania nanoparticles with PDMS • Subsequent etching 2.) Synthesize a suitable PDMS block copolymer

  6. Plasma etching of PDMS covered nanoparticles w/ nanoparticles 3 min 45 sec 7 min 30 sec w/o nanoparticles 15 min

  7. Photoluminescence of titania nanoparticles 398nm,470nm- self-trapped excitons localized on TiO6 octahedra 431nm- surface defects Considerable increase in the intensity of the peak after etching.

  8. Characterization of Samples • Methods Extracted Information • X-Ray Reflection (XRR) Film thickness • Scanning Electron Microscope (SEM) Morphology (real space) • Atomic Force Microscope (AFM) Topography (real space) • Grazing Incidence Small Angle Morphology • X-Ray Scattering (GISAXS) (reciprocal space) Further Options: SAXS, GIUSAXS, NR & SANS UV/Vis Spectroscopy, Photoluminescence (PL) Synchrotron beamline BW4, DESY HASYLAB Microfocussed beam size 30 x 60 m2 Wavelength  = 0.138 nm Sample detector distance d  2 m Incidence angle i  0.7 deg

  9. Scattering under grazing incidence GISAXS • Non-desctructive structural probe • NO special sample preparation required • Yields excellent sampling statistics  Averages over macroscopic regions to provide information on nanometer scale • Sensitive to surfaces and selective to materials • investigation of structures in the m- to nm-scale • Extracts information about: object geometry, size distributions & spatial correlations

  10. GISAXS of nanocomposite films Before calcination Detector scans Horizontal cuts c (PEO) Horizontal cuts c (TiO2) Ordered clustered nanoparticles Calcination After calcination Further ordering of nanoparticles

  11. Substrates w/ ordered nanoscale roughness Detector scans Horizontal cuts c (TiO2) Horizontal cuts c (TiO2) ITO w/o film ITO w/ film Glass w/film Glass w/o film ITO glass AFM: bare ITO AFM: ITO w/ film SEM: bare ITO

  12. GISAXS of plasma etched samples Detector scans Horizontal cuts c (PDMS) Horizontal cuts c (TiO2) I: O2 plasma etch, 15 min (Si/PDMS(TiO2) II: O2 plasma etch, 3:45 min (Si/PDMS(TiO2)) III:IV after calcination IV: as prepared (Si/PS-b-PEO(TiO2)) IV III II I

  13. Data treatment & simulation Vertical & horizontal cuts from measured 3D data Mathematical model  2D fit of horizontal cuts Physical model  Input of extracted parameters of mathematical fit  2D fit and 3D simulation of scattering pattern Fixed resolution peak 2. Structure peak 1. Structure peak

  14. Results of GISAXS • Successful preparation of desired morphologies of ordered nano- composite films  establishment of preparation • Working PDMS plasma etch process  Pre-test accomplished • Calcination induces further ordering • GISAXS investigation of ordered nanocomposite films on substrates with ordered nanoscale roughness • AFM & SEM results are in good agreement with GISAXS

  15. Crown ether PDMS did NOT grow in desired extent in THF PDMS synthesis: PDMS-b-PEO Synthetic approaches in literature • Coupling via hydrosilylation (Hüsing, Mascos) • good yield for low molecular weights (Mw) • for suitably high Mw: Yield ~ 2-5% (due to cleaning) • Sequential polymerization in presence of crown ethers (Meier)

  16. Own approach: Coupling of anionic polymerization and ATRP • Anionic polymerization of PDMS stopped by • Polymerization of PBMA carried out by ATRP • THF, RT, CuBr and ligand We have block with presence of homopolymers.

  17. HPLC graphs of PDMS-b-PBMA Light scattering measurement UV measurement

  18. Better attachment of ATRP initiator L. Bes, K. Huan, E. Khoshdel, M.J. Lowe, C. F. McConville, D.M. Haddleton, Eur. Poly. J. 39, 5-13 (2003) • ABA triblock copolymers synthesized with different molecular weights • Next step: Attachment of ATRP initiator by esterification of a carbinol group at the end of PDMS with 2-bromo-iso-butyryl bromide • Then PMMA polymerization by ATRP

  19. THF PDMS-CNO and PEO-OH 1. 2. 3. No block! THF, 35°C Catalyst: dibutyltin dilaurate THF, reflux K. Kim, K. E. Plass, A. J. Matzger JACS, 127, 4879 (2005)

  20. Results of synthesis • Desired block hard to be synthesized with shown approaches • Coupling with reactive end remains problematic • Preferred route: Coupling of anionic with ATRP  Different topologies (bottle brush)

  21. Outlook Characterization Setting up process cell  GISAXS in-situ investigation of templated hybrid films Reinforced simulation Synthesis PDMS-b-PEO by coupling of end groups (catalyst) PDMS-b-PHEMA  by attachment of ATRP initiator Material PDMS barrier layer properties (characterization) Optimized etch conditions & applied substrate materials Network GISAXS for other projects  sharing resources Developing new ideas

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