Epoxy-Based Hydrogels Investigated by High-Frequency Dielectric Relaxation Spectroscopy

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• 作者：Ivan Krakovsk媒 ; Toshiyuki Shikata ; Ryuta Hasegawa
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：November 14, 2013
• 年：2013
• 卷：117
• 期：45
• 页码：14122-14128
• 全文大小：374K
• 年卷期：v.117,no.45(November 14, 2013)
• ISSN：1520-5207

文摘

Using high-frequency dielectric relaxation spectroscopy, nanophase-separated structures of epoxy-based hydrogels were investigated as a function of water content at 25 掳C. The dielectric spectra resulting from the hydrogels were reasonably decomposed into two Debye-type and two Cole鈥揅ole-type relaxation modes. The fastest Debye-type mode, found at 8.3 ps, was attributed to the rotational relaxation process of free water molecules in the bulk state. The other Debye-type mode, at ca. 20鈥?4 ps, originates from the exchange process of water molecules that are hydrogen-bonded to the hydrophilic epoxy network portions for free bulk ones. The first Cole鈥揅ole-type mode observed, at ca. 20鈥?70 ps, was assigned to the complicated dynamics for electric dipole moments of the hydrophilic groups in the epoxy networks (mainly monomeric oxyethylene units). The slowest major Cole鈥揅ole-type mode, at 5鈥?9 ns, was attributed to the Maxwell鈥揥agner鈥揝illars polarization process and confirmed the presence of the nanophase-separated structures as revealed by the previous small-angle neutron scattering experiments.