Photon Factory Activity Report 2016 #34 (2017)

BL-6A/2015G711

Control of Carbon Layer Orientation in Phenolic Resin- and Polyimide-Based
Carbon Films by Dispersing Graphene Oxides
Yuji Demukai, Hiroki Ikegami and Masatoshi Shioya*
Tokyo Institute of Technology, 2-12-1-S8-34 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
1 Introduction
The present study intends to produce highly oriented
carbon films with enhanced carbon layer orientation inparallel to the film surface by high temperature
carbonization of polymers containing graphene oxides(GOs). It has been reported that the electrical conductivityof the carbon film derived from a resol type phenolic
resin containing GOs is twice as high as that of the carbon
film derived from "kapton" which yields a well-oriented
graphite film. [1] In this experiment, the comparison wasmade on the carbon layer orientation between the carbon
films derived from a resol type phenolic resin and apolyimide both containing GOs. The development of theorientation of GOs in the matrix polymers during drying
stage of the wet film forming process was investigated byusing the synchrotron radiation small-angle X-ray
scattering (SAXS).
2 Experimental
A resol type phenolic resin and a polyimide weredissolved in N,N-dimethyl formamide (DMF) separatelyand GOs with the layer size of 4 µm were added to thesesolutions. These mixtures were cast into a vessel and theprecursor polymer films were obtained by leaving thevessel in a draft chamber for evaporating DMF. The
carbon films were derived by high temperature
carbonization of the precursor polymer films in nitrogenoatmosphere at 1000 C for 10 min.
The SAXS measurements were performed at intervals
during the drying stage of the film forming process at BL6A in PF. The X-ray wavelength was 0.15 nm, thesample-to-detector distance was 2 m and the scattering
intensity was measured using Pilatus 3. The wide-angle
X-ray diffraction (WAXD) measurements of the precursor
polymer films and the carbon films were also performed.
From the full width at half maximum (FEHM) of theazimuthal distributions of SAXS and WAXD intensity, thedegree of orientation was calculated as (π-FWHM)/π.
The degree of orientation was determined for the GOs inthe precursor polymer films using SAXS and for thebenzene rings in the precursor polymer films and thecarbon layers in the carbon films using WAXD.
3 Results and Discussion
The SAXS and the WAXD of the precursor polymer
films are caused by the GOs and the stacks of benzene
rings, respectively. The WAXD of the carbon films iscaused by the carbon layer stacks in the matrix carbon
yielded from polymers. All these planar structurecomponents were preferentially oriented in parallel to thefilm surface. The degree of orientation of GOs andbenzene rings in the precursor polymer films, that of thecarbon layers in the carbon films and the electricalconductivity of the carbon films are shown in Table 1. It
is found that the electrical conductivity and theorientation of the carbon layers are higher for thephenolic resin-based carbon films as compared with thepolyimide-based carbon films. It is considered that during
the film forming process, the GOs are oriented in parallelto the film surface and the benzene rings of the polymer
chains are oriented in parallel to the GOs and during
carbonization process, the carbon layers oriented inparallel to the GOs are developed. The higher orientationof GOs in the precursor polymer films and the stronger
interaction between GOs and the methylol groups in resol
are considered to lead to the higher degree of carbon layer
orientation in the phenolic resin-based carbon films.
Table 1: Degree of orientation of GOs and benzene rings
in precursor polymer films, that of carbon layers incarbon films and electrical conductivity of carbon films.
Precursor polymer contained GOs with the size of 4 μmby 10 wt %.
Precursor
polymer
Phenolic resin
PolyimidePrecursor
polymer
Phenolic resinPolyimide

Precursor film
Orientation
Orientation ofof GOsbenzene rings
0.49
0.092
0.18
0.070
Carbon film
Orientation ofElectrical-1
carbon layers conductivity (S cm )0.54418
0.38
168

Acknowledgement
The authors are indebted to Profs. N. Igarashi, N.
Shimizu and T. Mori at PF for their experimental support.
Reference[1] H. Ikegami，T. Kato，H. Matsumoto，M. Shioya,
Fiber preprints, Japan, 70, 3B03 (2015).
*shioya.m.aa@m.titech.ac.jp