Carbohydrate Polymers 81 (2010) 919–924
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Preparation of nanoﬁbrillar carbon from chitin nanoﬁbers
, F. Kurosaki
, H. Yano
, M. Takano
Research Institute of Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011, Japan
Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto 606-8501, Japan
Received 21 August 2009
Received in revised form 27 January 2010
Accepted 7 April 2010
Available online 13 May 2010
Nanoﬁbrillar carbons were prepared by the carbonization of prawn chitin and wood cellulose nanoﬁbers.
Chitin and cellulose nanoﬁbers with the average width of 10 nm were obtained by a grinder treatment
from prawn shells and wood cell walls, respectively. Nanoﬁber aerogels prepared from nanoﬁber-
water suspensions by solvent exchange and freeze-drying were used as carbon precursors. Since chitin
nanoﬁbers did not ﬂocculate in organic solvents due to their low hydrophilicity, the aerogels of chitin
nanoﬁbers did not form wide bundles of coalesced nanoﬁbers. Furthermore, chitin nanoﬁbers had higher
thermal stability than wood cellulose nanoﬁbers. Thus, after the carbonization of chitin nanoﬁbers, the
original ﬁne and individual nanoﬁber network was maintained in the chitin carbon. In contrast, after the
carbonization of wood cellulose nanoﬁbers, the original nanoﬁber morphology was destroyed due to the
aggregations of wood cellulose nanoﬁbers and their low thermal stability.
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Chitin and cellulose are the most abundant bioresources on
earth—the former is found in arthropods, mollusks, and fungi, and
the latter is found in plants. Chitins are a yearly production of
tons. However, most of them are dis-
carded as industrial waste without effective utilization (Shahidi &
Synowiecki, 1991). Thus, it is important to make efﬁcient use of
this biomass resource as a natural and environmentally friendly
Recently, chitin and cellulose nanoﬁbers (also known as bio-
nanoﬁbers) with a diameter of 4–20 nm were obtained from squid
pens, crustacean exoskeletons, and wood cell walls (Abe, Iwamoto,
& Yano, 2007; Fan, Saito, & Isogai, 2008, 2009; Ifuku et al., 2009;
Iwamoto, Nakagaito, Yano, & Nogi, 2005; Saito, Nishiyama, Putaux,
Vignon, & Isogai, 2006). Moreover, chemical modiﬁcations of bio-
nanoﬁbers have also succeeded in the improvement of mechanical
properties of bionanoﬁber materials (Ifuku et al., 2007; Nogi et al.,
2006). The bionanoﬁber materials are the perfect candidate for con-
tinuous roll-to-roll processing in the future production of electronic
devices, such as ﬂexible displays, solar cells, e-papers, and a myriad
of new ﬂexible circuit technologies (Nogi, Iwamoto, Nakagaito, &
Yano, 2009; Nogi & Yano, 2008, 2009; Yano et al., 2005).
Corresponding author. Present address: Institute of Science and Industrial
Research, Osaka University, Ibaraki 567-0047, Japan. Tel.: +81 6 6879 8521;
fax: +81 6 6879 8522.
E-mail address: email@example.com (M. Nogi).
Thermal transformation of bionanoﬁbers without changing
their morphology via calcinations at elevated temperatures is effec-
tive procedure to impart new functionalities such as superior
mechanical properties, electrical and thermal conductivity, heat
and chemical resistance and so on. These properties of carbon
ﬁber make it very popular in aerospace, civil engineering, ﬁlter
medium, wind generator blades, and sporting goods. However,
since most biomasses would be destroyed during carbonization, it
is difﬁcult to preserve their nanostructures (Deng, Liao, & Shi, 2008;
Paris, Zollfrank, & Zickler, 2005; Polarz, Smarsly, & Schattka, 2002;
Yoshino, Matsuoka, & Nogami, 1990). For example, Yoshino et al.
(1990) found that when hydrogels of bacterial cellulose nanoﬁbers
were oven-dried, the nanoﬁber morphology was destroyed after
graphitization. However, when bacterial and tunicate cellulose
nanoﬁber aerogels with large surface areas, obtained by solvent
exchange (water–ethanol–t-butyl alcohol) and freeze-drying, were
carbonized or graphitized, the nanoﬁber morphology was main-
tained without melting (Ishida, Kim, Kuga, Nishiyama, & Brown,
2004; Kim, Nishiyama, Wada, & Kuga, 2001; Kuga, Kim, Nishiyama,
& Brown, 2002). Therefore, to carbonize bionanoﬁbers without
damaging their nanostructures, it is important to prepare nanoﬁber
aerogels having large surface areas.
To fabricate an aerogelwith a large surface area, it is important to
disperse bionanoﬁbers homogeneously in organic solvents, in order
to prevent ﬁber ﬂocculation. Chitin is a linear polysaccharide of ␤-
(1-4)-2-acetamido-2-deoxy-d-glucose. The chemical structure of
chitin is slightly dissimilar to that of cellulose with a hydroxyl group
replaced by an acetamido group. Therefore, chitin appears to have
an advantage over cellulose in that chitin nanoﬁbers disperse more
homogeneously in organic solvents than cellulose nanoﬁbers do.
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