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GISAXS による高分子薄膜構造解析

GISAXS による高分子薄膜構造解析. 東京大学 大学院新領域創成科学研究科 基盤科学研究系 物質系専攻 横山英明. yokoyama@molle.k.u-tokyo.ac.jp. Outline. Nanocellular thin films GISAXS What can we obtain using GISAXS? Distorted Wave Born Approximation (DWBA) ‏ Quantitative analysis of nanocellular thin films using DWBA

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GISAXS による高分子薄膜構造解析

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  1. GISAXSによる高分子薄膜構造解析 東京大学大学院新領域創成科学研究科基盤科学研究系物質系専攻横山英明 yokoyama@molle.k.u-tokyo.ac.jp

  2. yokoyama@molle.k.u-tokyo.ac.jp Outline Nanocellular thin films GISAXS What can we obtain using GISAXS? Distorted Wave Born Approximation (DWBA)‏ Quantitative analysis of nanocellular thin films using DWBA Analysis of vertically and horizontally aligned nanosheets

  3. yokoyama@molle.k.u-tokyo.ac.jp Foaming Styrofoam Macroscopic foam Macrocells Microfoaming with supercritical carbon dioxide Microscopic foam Microcells Target: smaller foams(cells)‏ Nanofoaming Nanocells

  4. yokoyama@molle.k.u-tokyo.ac.jp Supercritical Carbon Dioxide Solid SCF Pressure Pc Liquid Gas Tc Temperature Accessible critical point (Tc = 31.1 & Pc = 7.4 MPa)‏ Tunable density & solvent quality Environmentally friendly High diffusivity

  5. yokoyama@molle.k.u-tokyo.ac.jp Conventional CO2 foaming Process 10m Example: polystyrene Rapid depressurization Limited accessible size. > 1 mm *K. A. Arora, A. J. Lesser and T. J. McCarthy Macromolecules 1998, 31, 4614-4620

  6. yokoyama@molle.k.u-tokyo.ac.jp Self-assembly of block copolymers Block Copolymers present a variety of domain structures of the order of 5 – 50 nm. M. W. Matsen and M. Scick , Phys. Rev. Lett . 72 , 2660 (1994).

  7. yokoyama@molle.k.u-tokyo.ac.jp Block copolymer with fluorinated block Poly(styrene-block-perfluorooctylethyl methacrylate) (PS-PFMA)‏ Poly(methyl methacrylate-block-perfluorooctylethyl methacrylate) (PMMA-PFMA)‏ PFMA is soluble in SC CO2 (CO2-philic)‏ 5~50 nm

  8. yokoyama@molle.k.u-tokyo.ac.jp CO2 Process Solid SCF Pressure Pc Liquid Gas Tc Temperature 60 ºC Temperature /ºC isobaric 2 mm Depressurization 0 ºC 1 h Time / h Back pressure regulator CO2 pump High pressure vessel Failed: Microcells appear ?

  9. yokoyama@molle.k.u-tokyo.ac.jp Structures of nanofoams Nanocell A B PS domain PFMA domain (A) SAXS profiles of PS-PFMA processed in 7.5-30 MPa of CO2. Domain spacing increase with pressure. (B) A schematic picture of nanofoams and PS-PFMA chains.

  10. yokoyama@molle.k.u-tokyo.ac.jp Nanoces in thin films 70 nm ScCO2 pressurize (110 nm?)‏ ScCO2 depressurize 100 nm

  11. yokoyama@molle.k.u-tokyo.ac.jp Exposing cell structures by RIE 200 nm Etching 0 nm 10 nm 13 nm 15 nm 20 nm 40 nm

  12. yokoyama@molle.k.u-tokyo.ac.jp Reduction of refractive index　= porosity 1.6 0.6 0.5 1.5 0.4 1.4 Volume Fraction of cells 0.3 Refractive Index 1.3 0.2 0.1 1.2 0.0 1.1 0 5 10 15 20 25 30 P / MPa Refractive index (density) is controlled by the processing pressure of CO2.

  13. yokoyama@molle.k.u-tokyo.ac.jp Quantitative measurement of nanocells Prepare a single layer of nanocells (60 nm thick film)‏ 2-D hexagonal lattice inter-cell scattering is restricted in the film plane Foam factor of cells is 3D Size Structure of block copolymers around the voids

  14. yokoyama@molle.k.u-tokyo.ac.jp Grazing incident small angle X-ray scattering (GISAXS)‏ http://www.spring8.or.jp/wkg/BL40B2/instrument/lang-en/INS-0000001280/instrument_summary_view

  15. yokoyama@molle.k.u-tokyo.ac.jp GISAXS Patterns qz qy

  16. yokoyama@molle.k.u-tokyo.ac.jp Theory of GISAXS • Reflectivity • Fresnel law • Small Angle Scattering • Born Approximation • Fourier transform of model • GISAXS(DWBA)‏ • Calculate 4 beam intensities using Fresnel law • Apply Born approximation

  17. yokoyama@molle.k.u-tokyo.ac.jp Distorted Wave Born Approximation (DWBA)(1)‏ Compute Reflectivity.......

  18. yokoyama@molle.k.u-tokyo.ac.jp DWBA(2)‏ Compute scattering....... Tf Ti Ti Rf Tf Ri Rf Ri

  19. yokoyama@molle.k.u-tokyo.ac.jp Model r3 r2 R1 r1 R2 Lattice Form factor of cells F Paracrystal distortion qR

  20. yokoyama@molle.k.u-tokyo.ac.jp GISAXS and DWBA incident angle: 0.15 degree incident angle: 0.225 degree

  21. yokoyama@molle.k.u-tokyo.ac.jp Interference of reflected waves incident angle: 0.15 degree incident angle: 0.225 degree @ critical angle @ critical angle

  22. yokoyama@molle.k.u-tokyo.ac.jp Model fitting r3 r2 R1 r1 F R2 qR Sphere SCS

  23. yokoyama@molle.k.u-tokyo.ac.jp Self-assembly of block copolymers Block Copolymers present a variety of domain structures of the order of 5 – 50 nm. M. W. Matsen and M. Scick , Phys. Rev. Lett . 72 , 2660 (1994).

  24. yokoyama@molle.k.u-tokyo.ac.jp As cast morphologies TFT Top View HFB Top View • Trifluorotoluene (TFT) • Non-selective • Cylinders oriented in the surface plane • Hexafluorobenzene (HFB) • Selective for PFMA • Fat cylinders of PS oriented vertically ? HFB Side View

  25. yokoyama@molle.k.u-tokyo.ac.jp GISAXS of as-cast morphologies　 TFT GISAXS • Trifluorotoluene (TFT) • Non-selective • Cylinders oriented in the surface plane • Hexafluorobenzene (HFB) • Selective for PFMA • Fat cylinders of PS oriented vertically ? HFB GISAXS

  26. yokoyama@molle.k.u-tokyo.ac.jp CO2 process As-cast films CO2 process Templated porous films?

  27. yokoyama@molle.k.u-tokyo.ac.jp “Porous” structure (HFB)Standing nanosheets 200 nm

  28. yokoyama@molle.k.u-tokyo.ac.jp GISAXS of standing nanosheets 1 . 4 1 . 2 1 . 0 1 - 0 . 8 m n 5 10 / z q 0 . 6 4 10 0.20 0 . 4 3 10 Intensity, a.u. 2 0 . 2 10 0.15 1 10 0 . 0 0.10 - 1 . 2 - 1 . 0 - 0 . 8 - 0 . 6 - 0 . 4 - 0 . 2 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 0 10 - 1 q / n m -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 y -1 q / nm y

  29. yokoyama@molle.k.u-tokyo.ac.jp Standing nanosheets Top view • Capillary condensation • Constraint by substrate • 22.4 nm and 20.3 nm 200 nm

  30. yokoyama@molle.k.u-tokyo.ac.jp “Porous” structure (TFT)stacking nanosheets 200 nm

  31. yokoyama@molle.k.u-tokyo.ac.jp 1 . 4 a a = 0 . 1 5 = 0 . 2 0 R T 3 T T 3 1 - R T 2 m n T T 2 / z R T 1 q T T 1 Y o n e d a 0 - 1 . 2 0 1 . 2 - 1 . 2 0 1 . 2 - 1 - 1 q / n m q / n m y y Out of plane scattering

  32. yokoyama@molle.k.u-tokyo.ac.jp 8 10 1 1' 7 10 2 2' 6 10 1 3 1' 3' 2 5 10 Intensity, a.u. 2' 4 3 10 3' a = 0.15 3 10 a = 0.20 2 10 0.0 0.5 1.0 1.5 - 1 q / nm z Decomposing to two components 1,2,3 • Stacking nanosheets • 20.9±0.4 nm from 2p/Dqz of two sets of peaks 1',2',3'

  33. yokoyama@molle.k.u-tokyo.ac.jp Summary GISAXS reveals cellular structures quantitatively GISAXS is useful method for the analysis of thin films on substrate DWBA simulation is essential for quantitative analysis

  34. yokoyama@molle.k.u-tokyo.ac.jp Acknowledgment C. Dutriez, L. Li and R. Zhang (AIST)‏ K. Sugiyama (TIT)‏ S. Sasaki, H. Masunaga and M. Takata (JASRI)‏ H. Okuda (Kyoto U.)‏

  35. yokoyama@molle.k.u-tokyo.ac.jp In plane scattering 1 0 7 1 0 % 3 4 % 1 0 6 1 0 5 . u . a , I 1 0 4 1 0 3 1 0 2 - 1 . 5 - 1 . 0 - 0 . 5 0 . 0 0 . 5 1 . 0 1 . 5 q / n m - 1 y

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