Rangasamy Vijay Shankar, Thayumanasundaram Savitha, Seo Jin Won, Locquet Jean-Pierre
Department of Physics and Astronomy, KU Leuven, Bus 2414, Celestijnenlaan 200D, 3000 Leuven, Belgium.
Department of Physics and Astronomy, KU Leuven, Bus 2414, Celestijnenlaan 200D, 3000 Leuven, Belgium.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Mar 5;138:693-9. doi: 10.1016/j.saa.2014.12.004. Epub 2014 Dec 10.
We report the vibrational properties of sulfonated poly(ether ether ketone) (SPEEK) membranes, used as electrolytes in proton exchange membrane (PEM) fuel cells, studied by Fourier transform infrared (FTIR) spectroscopy. We discuss the changes in the vibrational modes of the functional groups present in the polymer arising due to the sulfonation process and the subsequent incorporation of silica particles functionalized with sulfonic acid group. From the infrared spectra, we confirm the incorporation of sulfonic acid group in the polymer chain as well as in the functionalized silica particles. We have also measured the variations in the peak area ratio of the characteristic out-of-plane vibrations of the aromatic rings in the PEEK polymer at 1280cm(-1) with respect to a reference peak at 1305cm(-1). These values were correlated to the crystallinity (XC) values experimentally determined by DSC technique, providing a non-destructive means to calculate the crystallinity of polymer membranes. The calculated XC values were in good agreement with the experimental values. The crystallinity was observed to decrease with increasing degree of sulfonation (DS), indicating the crystalline-to-amorphous phase modification of the polymer by sulfonation, which along with the enhanced ion-exchange capacity and water uptake, is responsible for the improved ionic conductivity at higher DS values.
我们报道了通过傅里叶变换红外（FTIR）光谱研究的磺化聚醚醚酮（SPEEK）膜的振动特性，该膜用作质子交换膜（PEM）燃料电池中的电解质。我们讨论了由于磺化过程以及随后引入用磺酸基团官能化的二氧化硅颗粒而导致的聚合物中存在的官能团振动模式的变化。从红外光谱中，我们证实了磺酸基团在聚合物链以及官能化二氧化硅颗粒中的引入。我们还测量了聚醚醚酮（PEEK）聚合物中芳香环在1280cm⁻¹处的特征面外振动的峰面积比相对于1305cm⁻¹处参考峰的变化。这些值与通过差示扫描量热法（DSC）技术实验测定的结晶度（XC）值相关，提供了一种计算聚合物膜结晶度的非破坏性方法。计算得到的XC值与实验值吻合良好。观察到结晶度随磺化度（DS）的增加而降低，这表明通过磺化聚合物从晶相到非晶相的转变，这与离子交换容量和吸水率的提高一起，是在较高DS值下离子电导率提高的原因。
