多面體聚矽氧烷與高分子複合材之氫鍵作用力與高分子電解質之研究

Abstract

多面體聚矽氧烷 (POSS) 衍生物於許多領域均有應用性。然而，探討其於高分子電解質及質子傳導膜方面(能源儲存及來源方面)應用之論文卻十分稀少。本論文中，改質後之多面體矽氧烷經由共價鍵結(化學鍵)及非共價鍵結(物理鍵)之方法導入高分子中，形成新型高分子電解質及質子傳導膜。此外，我們也利用Painter-Coleman association model (PCAM) 理論計算改質後多面體聚矽氧烷分子內作用力常數及其與高分子間作用力常數。 本研究首先探討具八酚官能基多面體聚矽氧烷分別與聚甲基丙烯酸甲酯 [poly(methyl methacrylate) (PMMA)]、聚乙烯必喀烷酮 [poly(vinyl pyrrolidone) (PVP)]，及兩者之共聚物 (PMMA-co-PVP) 形成摻合物之相溶性及作用力機制。二相混摻系統中，具八酚官能基多面體聚矽氧烷與聚甲基丙烯酸甲酯間之作用力常數為29，此常數小於聚乙烯苯酚 [poly(vinyl phenol) (PVPh)] 與聚甲基丙烯酸甲酯間之作用力常數 (37) 及乙基苯酚 [ethyl phenol (EPh)] 與聚甲基丙烯酸甲酯間之作用力常數 (101)。由上述可知，具八酚官能基多面體聚矽氧烷之酚官能基與聚甲基丙烯酸甲酯之羰基作用之機率較其他二者低。此外，我們也發現，具八酚官能基多面體聚矽氧烷之摻入可增加過氯酸鋰 (LiClO4) 與甲基丙烯酸甲酯－乙烯必喀烷酮共聚物 (PMMA-co-PVP) 高分子電解質之離子導電度。 接著觀察具八酚官能基多面體聚矽氧烷摻入過氯酸鋰與聚甲基丙烯酸甲酯高分子電解質後對於熱性質、形態，及作用力之影響。具八酚官能基多面體聚矽氧烷與聚甲基丙烯酸甲酯二相摻合物中，具八酚官能基多面體聚矽氧烷傾向自身聚集。因此，導致整體玻璃轉移溫度 (glass transition temperature) 下降。但於聚甲基丙烯酸甲酯、過氯酸鋰，與具八酚官能基多面體聚矽氧烷三相摻合物中，具八酚官能基多面體聚矽氧烷可形成約20奈米大小之聚集，導致整體之玻璃轉移溫度上升。傅立葉轉換紅外線光譜 (FTIR) 量測結果指出，過氯酸鋰有助於增加具八酚官能基多面體聚矽氧烷與聚甲基丙烯酸甲酯形成氫鍵作用力之機率。場發射掃描式電子顯微鏡 (SEM) 、熱示差掃瞄卡量計 (DSC) ，及X光繞射儀 (XRD) 之結果均指出，過氯酸鋰之摻入是可改善具八酚官能基多面體聚矽氧烷於聚甲基丙烯酸甲酯中之分散情形並使具八酚官能基多面體聚矽氧烷之物理效應由稀釋之角色轉為物理交聯之角色。 在本研究之最後一部分中，我們將多面體聚矽氧烷導入磺化聚醚醚酮 [sulfonated poly(ether ether ketone) (SPEEK)] 中，形成一新型交聯型質子傳導膜。在傳導膜中，奈米級交聯劑之分散性受其上有無磺酸根之影響而產生不同之分散程度，導致親水區域之分散及聯結程度不同。其中，含 17.5 wt% 交聯劑之新型質子傳導膜，具有高質子導電度 (0.0153 S/cm) 、低甲醇穿透率 (1.34 x 10-7 cm2/s) ，以及高選擇率 (0.0011 Ss/cm3) 之特性。

Polyhedral oligomeric silsequioxane (POSS) derivatives have the potential for the application in several fields, however, they had rarely been used in the filed of polyelectrolyte and proton exchange membrane which play a critical role in the people’s life because of the need for energy storage and cleaning energy source. In this thesis, POSSs were modified to be non-covalently and covalently incorporated into polymer matrix to form the new polyelectrolyte and proton exchange membrane. In addition, the Painter–Coleman association model (PCAM) was employed to theoretically study the intra-association and inter-association between the modified POSS and polymer. Firstly, we investigated the miscibility behavior and mechanism of interaction of poly(methyl methacrylate) (PMMA), poly(vinyl pyrrolidone) PVP, and PMMA-co-PVP blends with octa(phenol)octasilsequioxane (OP-POSS). For the PMMA/OP-POSS binary blend, the value of the association constant (KA = 29) was smaller than that in the poly(vinyl phenol) (PVPh)/PMMA (KA = 37.4) and ethyl phenol (EPh)/PMMA (KA = 101) blend systems, implying that the phenol groups of the OP-POSS units in the PMMA/OP-POSS blends interacted to a lesser degree with the C=O groups of PMMA than they did in the other two systems. In addition, the ionic conductivity of a LiClO4/PMMA-co-PVP polymer electrolyte was increased after blending with OP-POSS. Secondly, the thermal properties, morphologies, and interactions within the binary and ternary blends of poly(methyl methacrylate) (PMMA), octa(phenol)octasilsesquioxane (OP-POSS), and LiClO4 were described. In the binary PMMA/OP-POSS blends, the OP-POSS molecules tend to aggregate and result in a decrease (19 °C) in the glass transition temperature. In the ternary PMMA/LiClO4/OP-POSS blends, however, the OP-POSS molecules form small sphere-like domains (20 nm) leading to the composite’s glass transition temperature increasing by up to 30 °C. Based on these FTIR spectra, the addition of LiClO4 influenced the probability of hydrogen bonds formed between PMMA and OP-POSS and these SEM micrographs, DSC, and XRD data indicated that the addition of LiClO4 is a convenient and simple approach toward dispersing the OP-POSS nanoparticles within PMMA, where the presence of LiClO4 changes the physical effect of OP-POSS from that of a diluent role to a cross-linker role. Finally, polyhedral oligomeric silsequoixane (POSS) was incorporated into sulfonated poly(ether ether ketone) (SPEEK), forming a new cross-linked proton exchange membrane (PEM). The distribution of these nano-scale cross-linkers were affected by their sulfonic acid groups and dictated the water behavior and the dispersion and connectivity of hydrophilic domains within these PEMs. A PEM formed by incorporating 17.5 wt% of the cross-linkers (containing POSS molecules and sulfonic acid groups) into SPEEK exhibited high proton conductivity (0.0153 S/cm), low methanol permeability (1.34 □ 10–7 cm2/s), and high selectivity (0.0011 Ss/cm3).