Dielectric properties of hydrated or dehydrated ionic gels

制作了一套电介质测量系统。该系统在控制温度和屏蔽测量过程中的电磁波方面设计得很好。一种适应这种凝胶的细胞已经被开发出来。当测试样品的电导小于1uS时，得到0.1Hz ~ 1MHz频率范围内的介电谱。合成了以少量离子苯磺酸盐（0.5mo1%: NIPA- ss5; 0.1mo1%: NIPA- ss1; Omo1%: NIPA）为原料的n -异丙基丙烯酰胺聚合物凝胶，并用上述测量系统对其介电性能进行了测试。用我们所开发的方法，研究了凝胶中小离子扩散系数的温度依赖性。化学。Soc。日本。农业学报，69,2173-2178(1996))。从这些测量中，澄清了以下几点。1)小离子在崩塌型NIPA凝胶中的扩散系数是膨胀型凝胶中的百分之一。2)崩塌凝胶的电导也只有膨胀凝胶的百分之一左右。3)在坍塌状态下，NIPA- ss5凝胶在低（10Hz-100Hz）和高（1MHz）频率区域均有介电色散。4)膨胀态的NIPA=SS1和NIPA- ss5凝胶在0.2MHz附近出现分散性，而膨胀态的NIPA凝胶在0.2MHz附近没有分散性。这些结果有力地表明，坍塌凝胶中的水分子是电分离的，或者分散成孤立的簇（就像油中的水分子）。3)的结果表明，凝胶链上的离子基团与崩塌凝胶中的反离子之间形成了强离子对，结构水在水合状态下的弛豫频率在10Hz ~ 100Hz之间。这些结果已作为全文发表，部分内容已提交。

A system for the dielectric measurement has been made. The system is well designed to controll the temperature and to shield the electric wave during the measurement. A cell adapting to the gel has been developed. The dielectric spectra in the frequency range between 0.1Hz and 1MHz are obtained when the conductance of test sample is less than 1uS.The polymer gels of N-isopropylacrylamide, into which a small amount of ionic styrensulfonate(0.5mo1%: NIPA-SS5 ; 0.1mo1% : NIPA-SS1 ; Omo1%: NIPA)is introduced, have been synthesized and their dielectric properties have been examined by using the measuring system mentioned above. The temperature dependence of diffusion coefficients of small ions in the gel has been examined by using the method which we have developed(Bull. Chem. Soc. Jpn., 69, 2173-2178(1996)). From these measurements, the followings have been clarified. 1)The diffusion coefficient of small ion in the collapsing NIPA gel is one hundredth of that in the swelling gel. 2)The conductance of the collapsing gel is also about one hundredth of the swelling gel. 3)The dielectric dispersions are observed in the low(10Hz-100Hz)and high (1MHz)frequency regions for any of NIPA NIPA-SS5 gels in the collapsing state. 4)The NIPA=SS1 and NIPA-SS5 gels in the swelling state exhibit the dispersions around 0.2MHz but the NIPA gel in the swelling state doesn't. These results strongly indicate that the water molecules in the collapsing gels are electrically disconnected or disperse as isolated clusters(like the water molecules in oil). The result of 3)suggests that the strong ion-pair forms between the ionic group on the gel chain and the counter ion in the collapsing gels and that the relaxation frequency of structured water in the hydrated state is between 10Hz and 100Hz. These results have been published as a full paper and a part of them has been submitted.