鹼性燃料電池因其可使用非白金觸媒，有望降低價格，為近年來再生能源研究發展的一大趨勢；然薄膜研究上仍欠缺足夠條件使其商業化，其中最需克服的為同時擁有良好的離子導電度以及較低的燃料竄透。 本研究係利用分歧狀雙馬來醯亞胺聚合物（mBMI）和聚乙烯醇（PVA）之間形成semi-IPN（半互穿網絡）結構所製備的薄膜以降低乙醇的竄透率。同時，由於PVA及mBMI本身帶有親水官能基且相鄰醯亞胺基之間有利於氫氧根離子的傳遞，使此薄膜在鹼性溶液（KOH）下的離子導電度能隨添加mBMI的含量增加而有所提升，達到良好的離子導電度；另外，隨著添加mBMI含量增加，半互穿網絡交聯程度上升亦能使薄膜膨潤程度下降。 此外，本研究另一重點為以外加電場極化的狀態下製備成膜，可以將薄膜內部電負度較大的原子(如：O、N等)暴露以增加親水官能基，同時形成有序的親水離子傳導通道使非結晶區更為緻密。相較於無電場極化下的複合薄膜，在外加電場極化下的mBMI/PVA複合薄膜顯示出更優異的OH- 離子導電率（1.20*10 -2 S / cm 至3.82*10 -2 S / cm）、更低的乙醇竄透性（3.61*10 -7 cm 2 / s至7.77*10 -8 cm2 / s）， 以及極高的選擇率 (將近4*105)；此外，電場極化產生更緻密膜材結構，亦提高了薄膜的化學穩定性以及機械強度。 本研究顯示以外加電場的方式製備成膜可以提升離子導電度、降低燃料竄透以提升薄膜的選擇率，並同時提升薄膜的機械強度以及化學穩定性等物性，在最後ADEFC單電池測試中，薄膜亦相較於文獻中PVA薄膜有更卓越的表現，其電流密度達225 mA/cm2、功率密度達48 mA/cm2，顯示此類型薄膜可有效應用於鹼性燃料電池中。 ;A new category of hydroxide ion exchange membrane bearing ordered interpenetrating network (semi-IPN) structure established by electric field poling during membrane formation, lead to balanced property where high ion conductivity and low alcohol (methanol and ethanol) permeability co-existed. Success of this membrane preparation scheme is illustrated with the semi-IPN membrane formed by dendritic modified bismaleimide (mBMI) and polyvinyl alcohol (PVA) hydrogel casted together under applied electric field (E-field> 2000V/cm, Ac=1-20Hz,). Detailed morphology and water diffusion studies shows electric field poling establishes higher ordered amorphous domains that induces preferentially oriented conducting path that raised ion conductivity. On the other hand, semi-IPN network effectively reduces methanol and ethanol permeation and improves membrane toughness. When PVA:mBMI equals 2 to 3 weight ratio, the membrane delivered impressive room temperature OH ion conductivity of 38.2 mS/cm and a substantially reduced ethanol permeation of 7.7x10-8 cm2/s; giving exceedingly high ethanol selectivity ratio (>105) with electric field poling preparation. Ordering in the semi-IPN structure by electric field poling also causses densification of the amorphous domain that leads to improved chemical stability (99wt% mass retention in 6M KOH for nearly a month) and mechanical toughness (Tensile strength increased from 3.5 MPa to 7.0 MPa, and elongation at break raised from 60% to 92%). The study concludes the application of an external electric field initiated reorganization of membrane morphology where high performance fuel cell membrane bearing high ion conductivity; low fuel permeation; high membrane strength; and high chemical stability can be established, simultaneously.
