Pakalniete Laura Dace, Maskova Elizabete, Zabolockis Rudolfs Janis, Avotina Liga, Sprugis Einars, Reinholds Ingars, Rzepna Magdalena, Vaivars Guntars, Pajuste Elina
Institute of Chemical Physics, University of Latvia, Jelgavas Iela 1, LV-1004 Riga, Latvia.
Faculty of Chemistry, University of Latvia, Jelgavas Iela 1, LV-1004 Riga, Latvia.
Materials (Basel). 2023 Sep 6;16(18):6098. doi: 10.3390/ma16186098.
Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several advantages such as low cost, thermal and radiation stability and controllable physicochemical and mechanical properties, which depend on the degree of sulfonation (DS). Commercial PEEK was homogenously sulfonated up to a DS of 60-90% and the membranes were prepared using a solvent casting method. Part of the samples were irradiated with a 10 MeV electron beam up to a 500 kGy dose to assess the ionizing radiation-induced effects. Both non-irradiated and irradiated membranes were characterized by Fourier Transformation infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (H-NMR) spectroscopy, electrochemical impedance analysis and, for the first time for non-irradiated membranes, by spectrophotometric analysis with Cr(III). The above-mentioned methods for application for DS assessment were compared. The aim of this study is to compare different methods used for the determination of the DS of SPEEK membranes before and after high-dose irradiation. It was observed that irradiated membranes presented a higher value of DS. The appearance of different new signals in H-NMR and FT-IR spectra of irradiated membranes indicated that the effects of radiation induced changes in the structure of SPEEK materials. The good correlation of Cr(III) absorption and SPEEK DS up to 80% indicates that the spectrophotometric method is a comparable tool for the characterization of SPEEK membranes.
磺化聚醚醚酮（SPEEK）材料有望在质子交换膜（PEM）和直接甲醇燃料电池等应用中替代Nafion™。SPEEK膜具有多种优点，如成本低、热稳定性和辐射稳定性好，以及物理化学和机械性能可控，这些性能取决于磺化度（DS）。将商用聚醚醚酮均匀磺化至磺化度为60 - 90%，并采用溶液浇铸法制备膜。部分样品用10 MeV电子束辐照至500 kGy剂量，以评估电离辐射诱导的效应。通过傅里叶变换红外（FT - IR）光谱、热重分析（TGA）、质子核磁共振（H - NMR）光谱、电化学阻抗分析对未辐照和辐照后的膜进行了表征，并且首次对未辐照的膜采用Cr(III)分光光度分析进行表征。比较了上述用于评估磺化度的方法。本研究的目的是比较用于测定高剂量辐照前后SPEEK膜磺化度的不同方法。观察到辐照后的膜呈现出更高的磺化度值。辐照后膜的H - NMR和FT - IR光谱中出现不同的新信号，表明辐射诱导了SPEEK材料结构的变化。Cr(III)吸收与高达80%的SPEEK磺化度具有良好的相关性，表明分光光度法是表征SPEEK膜的一种可比工具。
