Saito Hironobu, Kato Shunpei, Matsumoto Keisuke, Umino Yuya, Kita Rio, Shinyashiki Naoki, Yagihara Shin, Fukuzaki Minoru, Tokita Masayuki
Graduate School of Science and Technology, Tokai University, Kanagawa 259-1292, Japan.
Graduate School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan.
Gels. 2018 Jun 22;4(3):56. doi: 10.3390/gels4030056.
Dynamics of solvent molecules restricted in poly (acryl amide) gels immersed in solvent mixtures of acetone⁻, 1,4-dioxane⁻, and dimethyl sulfoxide⁻water were analyzed by the time domain reflectometry method of dielectric spectroscopy and the pulse field gradient method of nuclear magnetic resonance. Restrictions of dynamic behaviors of solvent molecules were evaluated from relaxation parameters such as the relaxation time, its distribution parameter, and the relaxation strength obtained by dielectric measurements, and similar behaviors with polymer concentration dependences for the solutions were obtained except for the high polymer concentration in collapsed gels. Scaling analyses for the relaxation time and diffusion coefficient respectively normalized by those for bulk solvent suggested that the scaling exponent determined from the scaling variable defined as a ratio of the size of solvent molecule to mesh size of polymer networks were three and unity, respectively, except for collapsed gels. The difference in these components reflects characteristic molecular interactions in the rotational and translational diffusions, and offered a physical picture of the restriction of solvent dynamics. A universal treatment of slow dynamics due to the restriction from polymer chains suggests a new methodology of characterization of water structures.
采用介电谱的时域反射法和核磁共振的脉冲场梯度法，分析了浸泡在丙酮、1,4 - 二氧六环、二甲基亚砜与水的混合溶剂中的聚丙烯酰胺凝胶中受限溶剂分子的动力学。通过介电测量获得的弛豫时间、其分布参数和弛豫强度等弛豫参数来评估溶剂分子动力学行为的限制，除了塌陷凝胶中的高聚合物浓度外，还获得了与溶液中聚合物浓度依赖性相似的行为。对分别用本体溶剂的弛豫时间和扩散系数归一化后的弛豫时间和扩散系数进行标度分析表明，除了塌陷凝胶外，由定义为溶剂分子大小与聚合物网络网眼大小之比的标度变量确定的标度指数分别为3和1。这些组分的差异反映了旋转和平动扩散中特征性的分子相互作用，并提供了溶剂动力学限制的物理图像。由于聚合物链的限制导致的慢动力学的通用处理方法提出了一种表征水结构的新方法。
