質子交換複合膜Nafion(上標 ®)/SiO2之製備與特性研究

Preparations and Characterizations of the Nafion(superscript ®)/SiO2 Proton Exchange Composite Membrane

曹金萍(J. P Tsao) ； 林智汶(C. W. Lin)

《材料科學與工程》 34卷1期 (2002/03) Pp. 17-26

https://doi.org/10.6409/JMSE.200203.0017

摘要

本研究以溶膠－凝膠法製備複合型質子交換膜Nafion(上標®)/SiO2，並探討不同SiO2比例之質子交換複合膜的機械性質、熱性質、表面型態、氣體浸透率、及導離子能力等性質；由動態機械分析結果得知，經溶膠－凝膠法加入SiO2改質Nafion(上標®)膜，可明顯提高其在室溫及高溫(l00℃)之儲存模數(storage modulus, G')及損失模數(loss modulus, G”)，並發現Nafion(上標®)的三個玻璃轉移峰，分別為114.7℃的α轉移峰，12.0℃的β轉移峰，及-87.0℃的γ轉移峰，其中的α及β峰溫度均隨SiO2的增加而提高，惟代表主鏈的γ轉移峰溫度並未隨之改變，顯示SiO2可能只充塡於代表離子團的小空隙親水區；由原子力顯微鏡進一步對表面型態之觀察得知，SiO2確實首先充塡於支鏈離子團的區域，且隨著SiO2含量的增加，該區域逐漸減少，若SiO2的含量繼續增加時，SiO2會由已被填滿的小空隙區向外成長並聚集成塊狀。當SiO2含量在5.7%以下時，可降低複合膜之氧氣浸透率，但當SiO2含量更高時，則發現氧氣浸透率反而上升，可能是外層聚集的塊狀脆性擠壓之結果。低比例SiO2含量之複合膜不會影響離子交換容量及離子導電度，仍維持和純Nafion(上標®)膜相當之性質，其值約分別為0.86 mmole/g及1.8×10^(-2) S/cm。

關鍵字

Nafion(上標 ®) ； 溶膠－凝膠法 ； 二氣化矽 ； 質子交換膜

並列摘要

Proton-exchange membrane -Nafion(superscript ®) was modified by an in-situ sol-gel method to become a composite membrane containing silicate (SiO2). Mechanical and thermal properties, surface morphology, gas permeability, and ionic conductivity and ion exchange capacities of the proton-exchange composite membranes with different silicate contents were investigated in this study. According to the results obtained from the dynamic mechanical analyzer (DMA), both storage modulus (G') and loss modulus (G”) of the membrane increased with SiO2 content. Two of the three glass transitions (i.e. α and β transitions) temperatures increased with SiO2 content. However, the lowest transition (γ transition) temperature did not shift with the incorporation of SiO2. Atomic force microscopy (AFM) showed that the interstitial region (ions cluster region) of composite membrane was decreased with the increase of the SiO2 content and the surface morphology became agglomerated if the content of SiO2 increased further. Ionic conductivity and ion exchange coefficient (IEC) of the composite membranes were not much affected if lower SiO2 content was incorporated. We measured a value 0.86 mmole/g for IEC and l.8×10^(-2) S/cm for conductivity, respectively. These values are very closed to those reported in the literatures.

並列關鍵字

Nafion(superscript ®) ； Sol-gel ； Silicate ； Proton exchange membrane