Abstract In this study, plasma treatment is designed to solve phosphoric acid (PA) leaching problem as well as enhance the proton conduction and tensile strength of PBI membranes at high temperature. The hydrophily of polybenzimidazole (PBI) membrane surface is remarkably improved during plasma process according to the water contact angle decreasing from 84.0° to 9.9°. The effect of plasma generating power, gas pressure, Ar/O2 gas proportion and exposure time on water contact angle was investigated. The optimized plasma treating condition was 350 W, 5 Pa, 50 % O2 and 7 min. Fourier transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS) were performed to investigate the effects of plasma treatment on the chemical composition of PBI membranes. The results of FT-IR and XPS reveal the formation of oxygen groups and a progressive increase of oxygen content on the PBI membrane surface due to the plasma modification. Furthermore, the pristine-PBI and plasma-PBI membranes were doped into phosphoric acid (PA) for high temperature proton exchange membrane use. Compared with PA doped pristine-PBI, the PA doped plasma-PBI membranes were found to present higher PA doping levels, higher proton conductivity and better PA retention ability. This indicates plasma treatment could promote acid doping ability, maintain good mechanical strength and reduce PA leaching of PBI membranes.

中文翻译：

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等离子体处理增强聚苯并咪唑膜的磷酸保留和质子传导

摘要 在本研究中，等离子体处理旨在解决磷酸 (PA) 浸出问题，并提高 PBI 膜在高温下的质子传导和拉伸强度。随着水接触角从84.0°降低到9.9°，聚苯并咪唑（PBI）膜表面的亲水性在等离子体处理过程中得到显着改善。研究了等离子体发生功率、气压、Ar/O2气体比例和暴露时间对水接触角的影响。优化的等离子体处理条件为 350 W、5 Pa、50% O2 和 7 分钟。进行傅里叶变换红外光谱 (FT-IR) 和 X 射线光电子能谱 (XPS) 以研究等离子体处理对 PBI 膜化学成分的影响。FT-IR 和 XPS 的结果表明，由于等离子体改性，PBI 膜表面上形成了氧基团和氧含量逐渐增加。此外，原始-PBI 和血浆-PBI 膜被掺杂到磷酸 (PA) 中，用于高温质子交换膜。与 PA 掺杂的原始-PBI 相比，PA 掺杂的等离子体-PBI 膜表现出更高的 PA 掺杂水平、更高的质子传导率和更好的 PA 保留能力。这表明等离子体处理可以提高酸掺杂能力，保持良好的机械强度并减少 PB​​I 膜的 PA 浸出。将原始-PBI 和血浆-PBI 膜掺杂到磷酸 (PA) 中，用于高温质子交换膜。与 PA 掺杂的原始-PBI 相比，PA 掺杂的等离子体-PBI 膜表现出更高的 PA 掺杂水平、更高的质子传导率和更好的 PA 保留能力。这表明等离子体处理可以提高酸掺杂能力，保持良好的机械强度并减少 PB​​I 膜的 PA 浸出。将原始-PBI 和血浆-PBI 膜掺杂到磷酸 (PA) 中，用于高温质子交换膜。与 PA 掺杂的原始-PBI 相比，PA 掺杂的等离子体-PBI 膜表现出更高的 PA 掺杂水平、更高的质子传导率和更好的 PA 保留能力。这表明等离子体处理可以提高酸掺杂能力，保持良好的机械强度并减少 PB​​I 膜的 PA 浸出。