Ohkubo Takahiro, Ohira Akihiro, Iwadate Yasuhiko
‡FC-Cubic, National Institute of Advanced Industrial Science and Technology (AIST), 2-41-6 Aomi, Koto-ku, Tokyo 135-0064, Japan.
J Phys Chem Lett. 2012 Apr 19;3(8):1030-4. doi: 10.1021/jz3002458. Epub 2012 Apr 9.
An NMR method was applied for the deconvolution of specific water in sulfonated polyether sulfone membranes, where sulfonated polyethersulfone is a proton-conducting polymer in polymer electrolyte membrane fuel cells. The distribution of (1)H longitudinal relaxation times obtained by the inverse Laplace method was utilized to estimate the volume fraction of proton species as a function of relative humidity (RH). The relaxation time distribution clearly revealed two distinguished peaks on the order of 10(-3) and 10(-2) s, which corresponded to water in the larger and smaller channels for proton transports, respectively. We applied a pulse sequence to understand the water species by diffusion-weighted inversion recovery, which led to individual self-diffusion coefficients for deconvoluted water by using the longitudinal relaxation time. At 30% RH, the diffusion coefficient of water in small-sized channels is greater than that in large-sized channels. On the other hand, the diffusion coefficients of protons with smaller and larger water channels are almost the same at 50, 70, and 90% RH.
一种核磁共振方法被应用于对磺化聚醚砜膜中特定水的反褶积，其中磺化聚醚砜是聚合物电解质膜燃料电池中的一种质子传导聚合物。利用通过逆拉普拉斯方法获得的（1）H纵向弛豫时间分布来估计作为相对湿度（RH）函数的质子种类的体积分数。弛豫时间分布清楚地揭示了两个明显的峰，分别在10（-3）和10（-2）秒量级，它们分别对应于质子传输的较大和较小通道中的水。我们应用了一个脉冲序列，通过扩散加权反转恢复来了解水的种类，这通过使用纵向弛豫时间得到了反褶积水的各个自扩散系数。在30%相对湿度下，小尺寸通道中水的扩散系数大于大尺寸通道中的扩散系数。另一方面，在50%、70%和90%相对湿度下，具有较小和较大水通道的质子的扩散系数几乎相同。
