gisaxs による高分子薄膜構造解析
DESCRIPTION
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. [email protected]. Outline. Nanocellular thin films GISAXS What can we obtain using GISAXS? Distorted Wave Born Approximation (DWBA) Quantitative analysis of nanocellular thin films using DWBA - PowerPoint PPT PresentationTRANSCRIPT
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GISAXSGISAXS による高分子薄膜構造解による高分子薄膜構造解析析
東京大学東京大学 大学院新領域創成科学研究科大学院新領域創成科学研究科基盤科学研究系基盤科学研究系 物質系専攻物質系専攻
横山英明横山英明
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
Foaming
• Styrofoam– Macroscopic foam
• Macrocells• Microfoaming with supercritical carbon
dioxide– Microscopic foam
• Microcells• Target: smaller foams(cells)
– Nanofoaming• Nanocells
Accessible critical point (Tc = 31.1 & Pc = 7.4 MPa)
Tunable density & solvent quality
Environmentally friendly
High diffusivity
Supercritical Carbon Dioxide
Tc
Pre
ssur
e
Pc
Temperature
Gas
Liquid
SCFSol
id
Conventional CO2 foaming Process
Rapid depressurization Limited accessible size.> 1 m
10m
*K. A. Arora, A. J. Lesser and T. J. McCarthy Macromolecules 1998, 31, 4614-4620
Example: polystyrene
Self-assembly of block copolymers
M. W. Matsen and M. Scick, Phys. Rev. Lett. 72 , 2660 (1994).
Block Copolymers present a variety of domain structures of the order of 5 – 50 nm.
5~50 nm
Poly(styrene-block-perfluorooctylethyl methacrylate) (PS-PFMA)
Poly(methyl methacrylate-block-perfluorooctylethyl methacrylate) (PMMA-PFMA)
PFMA is soluble in SC CO2
(CO2-philic)
Block copolymer with fluorinated block
CO2 Process
Time / h
Tem
pera
ture
/ºC 60 ºC
0 ºC1 h
isobaric
Depressurization
CO2 pump
Back pressure regulator
High pressure vessel
TcP
ress
ure
Pc
Temperature
Gas
Liquid
SCFSol
id
Failed:Microcells appear
?
2 m
(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.
Structures of nanofoams
PFMA domain
PS domain
Nanocell
A B
Refractive index (density) is controlled by the processing pressure of CO2.
Reduction of refractive index = porosity
0 5 10 15 20 25 301.1
1.2
1.3
1.4
1.5
1.6
Ref
ract
ive
Ind
ex
P / MPa
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Vo
lum
e F
rac
tio
n o
f ce
lls
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
Grazing incident small angle X-ray scattering (GISAXS)
http://www.spring8.or.jp/wkg/BL40B2/instrument/lang-en/INS-0000001280/instrument_summary_view
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
Interference of reflected wavesincident angle: 0.15 degree incident angle: 0.225 degree
@ critical angle @ critical angle
Self-assembly of block copolymers
M. W. Matsen and M. Scick, Phys. Rev. Lett. 72 , 2660 (1994).
Block Copolymers present a variety of domain structures of the order of 5 – 50 nm.
As cast morphologies
• Trifluorotoluene (TFT)
– Non-selective
– Cylinders oriented in the surface plane
• Hexafluorobenzene (HFB)
– Selective for PFMA
– Fat cylinders of PS oriented vertically ?
TFT Top View HFB Top View
HFB Side View
GISAXS of as-cast morphologies
• Trifluorotoluene (TFT)
– Non-selective
– Cylinders oriented in the surface plane
• Hexafluorobenzene (HFB)
– Selective for PFMA
– Fat cylinders of PS oriented vertically ?
TFT GISAXS
HFB GISAXS
GISAXS of standing nanosheets
qy / nm-1
q z / nm
-1
-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
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.510
0
101
102
103
104
105
0.10
0.15
0.20
Inte
nsi
ty, a
.u.
qy / nm
-1
Standing nanosheets
• Capillary condensation• Constraint by substrate• 22.4 nm and 20.3 nm
Top view
200 nm
Out of plane scattering
= 0 .20 = 0 .1 5 RT 3
TT 3
RT 2
TT 2
RT 1TT 1
Y oneda
0 1 .2-1.20 1 .2-1 .2
qy / n m - 1
qz /
nm
-1
0
1 .4
qy / n m -1
Decomposing to two components
• Stacking nanosheets
• 20.9±0.4 nm from 2/qz of two sets of peaks
0.0 0.5 1.0 1.510
2
103
104
105
106
107
108
3'
3'
2'
2'
1'
1'
= 0.15 = 0.20
1
2
3
3
2
1
Inte
nsi
ty,
a.u
.
qz / nm- 1
1,2,3
1',2',3'
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
Acknowledgment
• C. Dutriez, L. Li and R. Zhang (AIST)
• K. Sugiyama (TIT)
• S. Sasaki, H. Masunaga and M. Takata (JASRI)
• H. Okuda (Kyoto U.)
In plane scattering
- 1 . 5 -1 .0 - 0 . 5 0 .0 0 . 5 1 . 0 1 .5
1 0 2
1 0 3
1 0 4
1 0 5
1 0 6
1 0 7
I,
a.u
.
q
y
/ n m - 1
1 0 %
3 4 %