Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

4A/2005C016

In-situ X-ray diffraction studies ofevaporation induced self-assembly process of mesostructured silica films
Hidenosuke ITOH1, Takashi NOMA*1, Hirokatsu MIYATA1, Kazuhiro TAKADA1,
1
2
Yasuhiro KAWASHIMA , Atsuo IIDA
1
Canon Research Center, Canon Inc., Ohta-ku, Tokyo 146-8501, Japan
2
KEK-PF, Tsukuba, Ibaraki 305-0801, Japan
Introduction
Mesoporous silica films have been widely investigatedin view points of synthesis, characterization andapplication. Recently, our group reported [1] that amesoporous silica film with highly aligned porous
structure was fabricated by dip-coating using a rubbingtreated polyimide film as an alignment layer. The initialstage of the dip-coating process is the key to solve theformation mechanism of mesostructured silica. Our group
has performed micro X-ray diffraction experiments ofmesostructured silica films under static conditions [2]. In
this report, we show our in-situ X-ray diffraction resultsof the formation of the mesostructured silica films withaligned porous structure .
Experimental
The mesostructured film was formed on a silica glass
substrate with a rubbing treated polyimide by evaporationinduced self-assembly (EISA) process. Figure 1 shows
our experimental setting for the substrate dipping into aprecursor solution. For the film formation, a reservoir wasmoved downward instead of pulling up the substrate toobserve the structural changes in a fixed area. The
rubbing direction was set to be parallel to the movementof the reservoir. The composition the precursor solution isBrij56 0.08: TEOS 1.0: Isopropyl alcohol 22: H2O 5: HCl0.004. In-situ micro beam XRD has been performed
under a reflection geometry at beam-line 4A of thePhoton factory, KEK. The beam size was 4.0 x 4.0 µm
and the energy 8 KeV. Two-dimensional (2D) XRD
patterns were collected by a high-speed CCD detector
with a time-resolution of 0.15 s.

Results and discussion
The formation of mesostructure has been achieved in avery short period. Figure 1 shows the 2-D XRD patterns
recorded, with the incident beam perpendicular to therubbing direction, after 25 s, 55 s, and 60 s from when themeasured area was apart from the solution surface.
Initially, no diffraction was observed, showing the lack ofany structural regularity. As shown in Fig. 2(a), a Debye
ring with high intensity was observed at 25 s, which
reveals the formation of a regular structure withpolycrystalline features. Interestingly, this Debye ring
disappeared once and weak spots suggesting the aligned
cylindrical micelle structure perpendicular to the rubbing
direction were obtained around 55 s. The diffraction spots
increase their intensity and the distance between them
became narrower with expansion of the structural period
as shown in Fig. 2(b). The alignment has been completed
around 60 s. From these results it is considered that (i) theinitially formed micelle structure is rearranged to thealigned cylindrical micelle structure in a short time scale.
(ii) the alignment is completed via the shrinkage of thestructural period.
25 s(a)rubbing direction
beam

Figure 1
Experimental setting for dipping thesubstrate into a precursor solution.

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Users' Report

60 s(b)Figure 2 Two-dimensional X-ray diffraction patterns
from the silica glass substrate with dipping speed of 100µm/s. The time indicated at the upper right of each figureis the time from when the measured area was apart fromthe solution surface.
References[1] H. Miyata et al., Chem. Mater., 17, 5323 (2005).
[2] T. Noma et al., PF activity report B., 177 (2004).
* noma.takashi@canon.co.jp