fabrication and evolution of mesostructures in fluorinated organosilicate mesoporous thin films...
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Fabrication and Evolution of Mesostructures in Fluorinated Organosilicate Mesoporous Thin Films
Ji-In Jung, Jae Young Bae and Byeong-Soo Bae*Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea
*E-mail: [email protected] http://www.sol-gel.net/lomc
Department of Materials Science and EngineeringKorea Advanced Institute of Science and Technology (KAIST)
Introduction
PFASs with long perfluoroalkyl chains act as a structure directing agent.
Different interaction with templates cause the different mesostructure formation
range.
The chain length of PFASs affected the formation of mesostructure and thermal-
induced mesostructure change.
The increase of calcination temperature caused the change of the composition,
mesostructure, and optical property in the mesoporous fluorinated organosilicate
films.
Conclusions
Experiments
Self-Assembly of Surfactants
0.01N HCl
Add methanol
Filtering & spin coating
Heat treatment
TMOS
PFASs
3-FPTMS
13-FOTES
17-FDTMS
SiF3C
OR
OROR
CF2
SiF2C
CF2
F2C
CF2
F3COR
OROR
SiOR
ORORC
F2
F2C
CF2
F2C
CF2
F2C
CF2
F3C
Surfactants for Experiment
Experimental Purposes
Fluorinated mesoporous organosilicate
films
Mesoporous silica films
PFASs with perfluoroalkyl
groups
Synthesis of fluorinated mesoporous organosilicate films with surfactants and chain lengths of PFASs
Physical characteristics of fluorinated films depending on chain lengths of PFASs and kind of surfactants
→ Optical property (n) & hydrophobicity & formation scheme
Thermal induced mesostructure and composition change
XRD Patterns of the Films Confirmation of Perfluoroalkyl Groups PFASs Chain Length Effect
Fabrication of Films with Pluronic F68
Thermal-Induced Mesostructure Change Future Works
Kind of Mesoporous Structures
Used in membrane, sensor, and optical and electroni devices.
→ Investigation of microstructure, composition and optical
property in the fluorinated organosilicate films
Evaporation Induced Self-Assembly (Film)
Experimental Routes
PFASs
Unit cell parameter /nmContact
angle / o
Mesoporous
structure
Refractive
indexAs-
synthesizedCalcined
3-FPTMS 4.34 3.00 67.7Hexagonal 1.268
Cubic 1.135
13-FOTES 4.53 3.92 99.1 Hexagonal 1.256
17-FDTMS 4.86 4.17 108.4 Hexagonal 1.240
PFASs with long perfluoroalkyl chain act as templates!
PFASs, the Role of Templates
Fabrication of Films with CTACl
XRD Patterns of the Films Thermal Analysis of the Films
XRD patterns
Comparison of Mesostructure Formation
Formation Scheme
Possibilities for a variety of application in optics !
The increase calcination temperature cause the decomposition perfluoroalkyl groups.
References
1600 1400 1200 1000 800 600 400
(c) (b) (a)
after 450oC calcined
after 350oC calcined
as-synthesized
Ab
so
rba
nc
e (
a.u
.)
Wave number (cm -1)
(a) 1060 cm-1
Asymmetric stretching
mode of Si-O-Si bond
(b) 1146 cm-1
Bending mode of Si-CH2 of
perfluoroalkylsilane
(c) 1206 cm-1
Symmetric stretching mode
of C-F bond of
perfluoroalkyl chain
Mesoporous fluorinated
organosilicate thin films
were calcined at 350 oC.1 2 3 4 5 6 7 8 9
3-FPTMS
13-FOTES
17-FDTMS
Inte
nsi
ty (
a.u
.)
2 (degree)
x3
2 3 4 5 6 7 8
(f)650oC
550oC
450oC
350oC
(e)
(d)
(c)
(b)
(a)
150oC
as-synthesized
Inte
nsi
ty (
a.u
.)
2 (degree)
As-synthesized 150 C 350 C 450 C 650 C0.0
0.2
1.2
1.4
1.381.351.2261.441.457
o oo o
Re
fra
cti
ve
In
de
x
Heat Treatment
17-FDTMS3-FPTMS 13-FOTES
0 100 200 300 400 500 6000.0
0.2
0.4
0.6
0.8
1.0
1.2
Ato
mic
Ra
tio
Temperature (oC)
O/Si C/Si F/Si
1 2 3 4 5
Inte
nsi
ty (
a.u
.)
2 (degree)
SubstrateF68(Cubic)
SubstrateP123 (Hexa)
SubstrateF68 (Cubic)P123 (Hexa)
Substrate
100 nm
91 nm
133 nm
Hexagonal Cubic LamellarCubic
Amphiphilic surfactant
Hydrophilic head Group
Hydrophobic tail
Surfactant concentration increase
Micelle
Burn off surfactant
Surfactant+
Inorganic precursor
(Silica et al.)
Formation of Mesoporous Materials
Inorganic-Organic Hybrid Mesoporous Materials
Si OCH3
OCH3
OCH3
H3CO
Stirring for 24 hr
Add surfactant
TMOSPFAS + 0.01 N HCl
[CHCH33(CH(CH22))xxN(CHN(CH33))33]Cl]Cl
CTACl (x=15)CTACl (x=15)
Alkyl-ammonium halide cationic surfactant
Hydrophilic head group
Hydrophobic tail group
CH2CH2O CH2CHO
CH3
HO HN/2
CH2CH2ON/2
M
PEO : Hydrophilic (water-soluble)
PPO : Hydrophobic (water-insoluble)
PEO-PPO-PEO triblock copolymer
Pluronic F68 (N=153, M=29)
Spherical micelle
After calcined
[ CTACl ] / [ TMOS ] (x263)
50 43 40 35 30 20 1510
H C
H
H
H H H H
Silica
3-FPTMS
13-FOTES
17-FDTMS H
C C
H H HH
H
H
H C* C
H
H
H : HexagonalC : CubicC* : Hexagonal/Cubic
2 4 6 8 10
d(100) a0
6.54 nm 7.55 nm
d(100) a0
6.31 nm 7.28 nm
d(100) a0
6.31 nm 7.28 nm
d(100) a0
5.97 nm 6.89 nm
200
200
200
200
100
100
100
100
R'=8
R'=4
R'=2
R'=6
Inte
nsit
y (a
.u.)
2 (degree)
2 4 6 8 10
d(100) a0
5.59 nm 6.45 nm
d(100) a0
5.48 nm 6.33 nm
d(100) a0
6.22 nm 7.18 nm
d(100) a0
5.93 nm 6.85 nm
200
200
200
200
100
100
100
100
R'=8
R'=6
R'=4
R'=2
Inte
nsit
y (
a.u
.)
2 (degree)
2000 1600 1200 800
(c)(b)(a)
550oC
450oC
400oC
350oC
As-synthesized
Ab
so
rba
nc
e (
a.u
.)
Wavenumber (cm -1)
0 100 200 300 400 500 600 700 80040
50
60
70
80
90
100
Temperature (oC)
We
igh
t (%
)
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
De
riv. We
igh
t (% / oC
)
Fluorinated Mesoporous
Silica Mesoporous
[Surfactants] / [Silanes]
5 10 15 20 25 30 454035
CTACl
F68
CTACl
F68
J.I. Jung; J.Y. Bae; B.S. Bae J. Mater. Chem. To be submitted (2004). J.I. Jung; J.Y. Bae; B.S. Bae Chem. Mater. To be submitted (2004). J.Y. Bae; J.I. Jung; B.S. Bae J. Mater. Res. To be submitted (2004). J.Y. Bae; O.H. Park; J.I. Jung; K.T. Ranjit; B.S. Bae Micropor. Mesopor.
Mater. 67, 265 (2004). O.H. Park; S.Y. Seo; J.I. Jung; J.Y. Bae; B.S. Bae J. Mater. Res. 18,
1039 (2003). C.J. Brinker; Y. Lu; A. Sellinger; H. Fan Adv. Mater. 11, 579 (1999). A. Stein; B.J. Melde; R.C. Schroden Adv. Mater. 12, 1403 (2000). G. Wirnsberger; B.J. Scott; B.F. Chmelka; G.D. Stucky Adv. Mater. 12,
1450 (2000).
FT-IR spectroscopy
As-synthesized After calcined FT-IR spectroscopy
Pluronic F68 copolymer decomposes above 350 oC.
Mesoporous fluorinated organosilicate thin films
were calcined at 400 oC.
TGA Curves
Silica wall
Fluorinated group
Although surfactant concentration is very low, mesoporous films are mainly formed by long perfluoroalkyl chain (As template).
Mesostructure Changes Compositional Change Refractive Index Change
20nm
20nm
3-FPTMS and CTACl After calcination at 550 oC, the cylindrical pores are maintained.
350 oC 550 oC
20nm
20nm
17-FDTMS and CTACl After calcination at 550 oC, a less ordered and broken mesostructure was formed.
350 oC 550 oC
Multi-mesostructured Films
Photochromic Dye- Applicable for optical waveguide, shutters,
light modulators, and optical storage media- For optical shutter applications, a fast
response time is required. - Study about the effect of hydrophobicity and
pore size
OH
OH
OH
HO
OH
OH
OH
O H
O H O H
HO
HO
<Hydrophilic>
CFn
CFn
CFn
CF
n
CF
n
CF
n
CF
n
CF
n
CF
n
Fn
CFn
C
F n
C
<Hydrophobic>
Fast response time
& long switching
cycle is expected.
1 2 3 4 5 6 7 8 9
3-FPTMS
13-FOTES
17-FDTMS
x2
Inte
nsi
ty (
a.u
.)
2 (degree)
It is possible to form the multi-layered films with thickness and different pore surface property such as pore size and pore structure.
[Multi-layer with different pore size and pore structure]
As-synthesized
F68 used
- The repulsionrepulsion of
hydrophobic
perfluoroalkyl chain &
hydrophilic PEO chain.
CTACl used
- The hydrophobic hydrophobic
interactioninteraction of
hydrophobic chain of
CTACl & hydrophobic
perfluoroalkyl chain.