著者

小林 秀雄 浦川 理 金子 文俊 井上 正志

出版者

The Society of Rheology, Japan

雑誌

日本レオロジー学会誌 (ISSN:03871533)

巻号頁・発行日

vol.42, no.1, pp.19-23, 2014

被引用文献数

4

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The δ-cocrystal of syndiotactic polystyrene (sPS) can capsulate various small guest molecules in the cavity of the crystalline region. We examined the rotational motion of isolated polar guest molecule, benzonitrile (BN), caged in the crystalline cavities by dielectric spectroscopy and the results were compared with the previously reported data of sPS / methyl ethyl ketone (MEK) system. The relaxation of BN in the crystalline region was specified from the comparison with the dielectric data of atactic-PS / BN system in which only the amorphous phase exists. The rotational relaxation time of BN in the crystalline cavity was 6 orders of magnitude longer, and the activation energy of BN was twice larger than those of MEK. These results suggest that spatial restriction due to the small cavity size strongly retards the rotational dynamics of the larger guest molecule, BN. Two-site model could successfully describe the temperature dependence of the dielectric intensity for sPS / BN system, revealing that there exist two stable states of BN molecules with energy difference of 7.42 kJmol^{<font size="-1">-1</font>} in the crystalline cavity.

著者

Yusuke Yasuda Hiroki Matsunobu Tetsuharu Narita Hideaki Yokoyama Koichi Mayumi Kohzo Ito

出版者

The Society of Rheology, Japan

雑誌

日本レオロジー学会誌 (ISSN:03871533)

巻号頁・発行日

vol.48, no.3, pp.161-168, 2020-06-15 (Released:2020-07-15)

参考文献数

27

被引用文献数

1

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In slide-ring (SR) gels, polymer chains are cross-linked by rings and can slide through the cross-linking points. The high chain mobility in SR gels is responsible for their unique physical properties such as softness, high deformability, and crack resistance. In this study, the dynamics of the polymer network in SR gels was investigated by the microrheological technique. The diffusion coefficients of the silica nanoparticles in SR gels with different cross-linking densities were measured by dynamic light scattering (DLS). It was found that the diffusion coefficient of the probe particles in the SR gels does not decrease monotonically with increasing cross-linking density even though their mesh sizes are close to the particle size. This suggests that the slidability of the cross-linking points enhances fluctuation of the polymer networks in the SR gels.