Solvent-free chemical modification of fullerene C60 by an amino-terminated polyethylene glycol

Solvent-free chemical modification of fullerene C60 by an amino-terminated polyethylene glycol

CARBON 4 7 ( 20 0 9 ) 1 2 0 7–12 0 8 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/carbon Tanso 235—Abstracts Contr...

70KB Sizes 0 Downloads 33 Views

CARBON

4 7 ( 20 0 9 ) 1 2 0 7–12 0 8

available at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/carbon

Tanso 235—Abstracts Control

carbon

dispersion in ethanol. The effect of C60 particle size on the yield

cryogel porous structures as electrodes for electric double-layer

and

behaviors

of

resorcinol-acetaldehyde

was found to be more significant than the stirring rate. Therefore,

capacitors

the SFM is more sensitive to the collision frequency between C60

Yusuke Kuwabara, Hironori Yano, Yoshiaki Kanematsu, Hirokazu

and amino-PEG compared to the diffusion of C60 in amino-PEG. In

Oda

order to understand the chemical modification mechanism, sim-

Faculty of Engineering, Kansai University, High Technology Research Center, 3-3-35 Yamate-cho, Suita 564-8680, Japan

ulation was performed based on a shrinking-core model assuming a chemical reaction as a rate limiting step. Using this model it was possible to estimate the number of amino-PEG molecules

The porous structures of mesoporous carbon materials, which

attached to C60. The results of simulation are a good fit to the

are known to be effective energy storage systems, were manipu-

gel permeation chromatography (GPC) data collected in the early

lated and their behaviors as electric double-layer capacitor elec-

period of the reaction considering that there is one amino-PEG

trodes were evaluated. Resorcinol (R) as the raw material and

attached to C60. As for the final period of reaction, the number

acetaldehyde (A) as the cross-linking agent were used to synthe-

of attached amino-PEG molecules increases according to the

size RA hydrogels via sol-gel polycondensation in a slightly basic

GPC data but the simulation shows an opposite tendency. This

aqueous solution. The RA hydrogels were freeze-dried and subse-

tendency was explained by a decrease in C60 surface activity

quently pyrolyzed at 1073 K for 30 min (heating rate, 10 K/min) to

and by additional reaction between products in the fluid phase.

obtain the RA carbon cryogels. The obtained samples were con-

[TANSO 2008;(235):268–74.]

firmed to have a high mesoporous carbon content, with a primary

doi:10.1016/j.carbon.2008.11.021

pore size diameter distribution of 20–40 nm. Due to a high ratio of ion adsorption and desorption capacitances, the samples were effective electrode materials capable of high-speed electrical charge and discharge for use as electrode materials of electric double layer capacitors. [TANSO 2008;(235):263–7] doi:10.1016/j.carbon.2008.11.020

Small-angle X-ray scattering study on structure of adsorbed molecular assemblies in carbon micropores Taku Iiyama, Sumio Ozeki Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan The in situ small-angle X-ray scattering (SAXS) of water and

Solvent-free chemical modification of fullerene C60 by an

CCl4 adsorbed on pitch-based activated carbon fibers (ACF) was

amino-terminated polyethylene glycol

measured at 303 K. We extended the Debye–Bueche theory to

Manabu Okuyamaa, Akira Teramotob, Masaru Watanabeb,

the 3-phase mixed system (solid phase: carbon, adsorbed phase,

Hiroshi Inomatab

and vacant space) to obtain the average dimension of each phase

a

(ls, la, and lv). The la of water in a wider pore system (pore width:

Process Engineering Lab, Mitsubishi Chemical, Group Science and

Technology Research Center, Inc., 1000 Kamoshida-cho, Aoba-ku, Yokohama 227-8502, Japan b

Research Center of Supercritical Fluid Technology, Tohoku University,

6-6-11-414 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan The solvent-free chemical modification (SFM) of fullerene (C60) by polyethylene glycol with amino termination (amino-PEG) was

w = 1.13 nm) increases with the fractional filling /. On the other hand, la in a smaller pore system (w = 0.75 nm) does not change with /. These results show the difference in the cluster growing process with the pore width. It seems that the difference in the size and shape of water clusters in the adsorption and desorption processes should lead to adsorption hysteresis. The developed analysis method may give direct information on molecular

studied in order to improve fullerene dispersability. The effect

assemblies in micropores.

of the stirring rate and the C60 particle size on the modification

[TANSO 2008;(235):275–9.]

yield was investigated in the temperature range 60–120 °C for

doi:10.1016/j.carbon.2008.11.022

3–24 h. As a result, 65% of C60 was modified at 60°C for 24 h for

doi:10.1016/S0008-6223(08)00623-4