JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

4-08
Synthesis of Functional Polycarbosilane Nano-fiber by
Ion Beam Induced Graft Polymerization
K. Yoshimura a) , M. Sugimoto a) , A. Idesaki a) , M. Yoshikawa a) and S. Seki b)
a) Environment and Industrial Materials Research Division, QuBS, JAEA,
b) Department of Applied Chemistry, Osaka University
Recently, we have synthesized the polycarbosilane (PCS)
nano fiber by ion beam irradiation and obtained silicon
carbide (SiC) nano fiber by firing of this PCS nano fiber 1) .
Because of the quite large surface area of nano fiber, the
metal-loaded SiC nano fiber has potential use as functional
materials of catalysts. To date, radiation-induced graft
polymerization and subsequent metal chelation step has been
2)
used for metal loading . In general, radiation-induced graft
polymerization, which is key step of such metal loading
process, is performed by electron-beam or -ray irradiation.
For PCS nano fiber prepared by ion beam irradiation, the
graft chain will be grown by induced radicals on the PCS
nano fibers after ion beam irradiation. In this study, we
synthesize functional PCS nano fiber by ion beam induced
graft polymerization. The introduction of graft chain was
examined on the basis of AFM measurement of nano fibers
with and without grafting process. The SiC fiber was also
prepared by firing of this material.
PCS (NIPUSI Type-A), as a ceramic precursor polymer,
was purchased from Nippon Carbon Co. LTD and was
spin-coated on a Si substrate. The coated PCS was
irradiated using 450 MeV 129 Xe 23+ ion beam. The irradiated
films were treated by dry, degassed toluene solution of
glycidyl methacrylate (GMA) and the insoluble irradiated
part of the film was developed as GMA grafted PCS nano
fiber. Then the samples were fired at 1,273 K in argon to
obtain SiC nano fiber. The sizes and shapes of the nano
fibers were observed using a SPA-400 atomic force
microscope (AFM) from Seiko Instruments, Inc.
Investigations of the grafted PCS nano fiber by AFM
were performed in order to identify the graft reaction
proceeded. Figure 1a and 1b show the AFM micrograph of
PCS nano fiber and grafted PCS nano fiber, respectively.
As can be seen, the radii of grafted PCS nano fiber were
larger than the PCS nano fiber. The radii of PCS nano fiber
were 8 nm, while the radii of grafted PCS nano fiber were
20 nm. Generally, grafted polymer fiber was thicker than
the starting polymer fiber 3) . Therefore, increases of the
radii suggest that graft polymerization proceeded on the PCS
nano fiber similar to the bulk fiber. Thus, GMA grafted
PCS nano fiber was successfully synthesized.
Figure 1c and 1d show AFM micrograph of SiC nano
fiber produced by firing of PCS nano fiber and grafted PCS
nano fiber, respectively. The PCS nano fiber shrank
30-40% reduction in the radii after firing. On the other
hand, the radii of SiC nano fiber obtained from grafted PCS
nano fiber were almost the same before and after firing.
This result suggested that most of graft chain is converted to
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amorphous carbon on SiC nano fiber via firing process.
The GMA grafted PCS nano fiber and its firing material
may have potential applications as nano catalyst supports and
as nano catalysts.
References
1) M. Sugimoto et al., Trans. Mater. Res. Soc. Jpn. 33,
(2008) 1027.
2) N. Seko et al., Nucl. Instrum. Meth. B 265 (2007) 146.
3) A. Sekine et al., Radiat. Phys. Chem. 79 (2010) 16.
(a) (b)
(c)
(d)
200 nm
200 nm
Fig. 1. AFM micrograph of (a) PCS nano fiber, (b)
GMA grafted PCS nano fiber, (c) SiC nano fiber
produced by firing of PCS nano fiber at 1,273 K in
argon, and (d) SiC nano fiber produced by firing of
GMA grafted PCS nanofiber at 1,273 K in argon.
Nano fiber was formed by 450 MeV 129 Xe 23+ ion
beam irradiation at a fluence of 1 × 109 ions cm -2 .