四甲基氢氧化铵改性聚偏氟乙烯一步接枝丙烯酰胺基甲基丙磺酸膜的研制

Preparation and Characterization of Membranes Synthesized via One-Step Grafting Acrylamido-Methyl Propane Sulfonic onto Poly( Vinylidene Fluoride) Modified by Tetramethylammonium Hydroxide

利用一步合成法,将2-丙烯酰胺基-2-甲基丙磺酸(AMPS)直接接枝到四甲基氢氧化铵(TMAH)改性的聚偏氟乙烯(PVDF)基质中,制得PVDF-g-AMPS膜。采用傅里叶变换红外光谱和能谱扫描电镜检测膜的结构、形貌及硫的分布,并研究了不同质量分数的TMAH对此膜电导率和甲醇渗透率的影响。结果表明,TMAH改性PVDF脱去HF产生C=C且AMPS成功接枝到PVDF上,硫元素在膜内外分布均匀;膜的电导率和甲醇渗透率随TMAH含量的增多而增大,TMAH质量分数为20%时,室温下电导率最大为0.0857 S/cm,甲醇渗透率为3.56×10-7cm2/s。热重分析表明,膜的热稳定性良好,耐热温度高达260℃。该膜作为电解质材料的直接甲醇燃料电池(DMFC)功率密度达到18.81 m W/cm2。

The new method of single-step synthesis was applied to prepare poly（ vinylidene fluoride）（ PVDF） directly grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid（ PVDF-g-AMPS） membranes. By this new method,PVDF was modified with the tetramethylammonium hydroxide（ TMAH） in advance. The microstructures,morphologies,and sulfur distribution of the membrane were characterized by FT-IR,SEM,and energy-dispersive X-ray spectroscopy（EDX）. The effects of the TMAH mass fraction in methanol solution on proton conductivity and methanol permeability of the membranes were investigated. Experimental results show that PVDF is dehydrofluorinated by TMAH and obtained carbon-carbon double bond. AMPS is successfully grafted onto PVDF; the distribution of sulfur is homogeneous in the interior and surface of the membrane. The proton conductivity of proton exchange membrane and the methanol permeability increase with the TMAH mass fraction in methanol solution,and when the content of TMAH is 20%,the proton conductivity of membrane is 0. 0857 S / cm at ambient temperature and the methanol permeability coefficient is 3. 56 ×10- 7cm2/ s. Besides,the membranes exhibit excellent thermal stability up to approximately 260 ℃,verified by thermal gravimetric analysis（ TGA）. The peak power density of direct methanol fuel cell（ DMFC） fabricated with above membrane is 18. 81 m W / cm2.