多孔骨架薄膜之相態工程與結構設計：從結晶異質介面到溶劑揮發誘導組裝

Abstract

金屬有機框架（metal–organic frameworks, MOFs）與共價有機框架（covalent organic frameworks, COFs）因具有高度可設計的孔洞結構、高比表面積、可調控的表面化學性質與多樣化的框架組成，已成為近年來重要的多孔材料平台。然而，傳統 MOFs 與 COFs 多以粉末型態被合成與研究，在實際裝置應用中仍面臨許多限制，例如薄膜連續性不足、顆粒間傳輸阻力增加、界面接觸不良，以及孔道無法有效連接等問題。尤其在離子傳輸、滲透能發電與電化學感測等應用中，材料不僅需要具備內在孔洞功能，更需要形成連續且可控制的薄膜或膜材料結構。因此，本論文以「多孔骨架薄膜之相態工程與結構設計」為核心，探討如何透過異質介面設計與非晶介孔薄膜構築，將多孔框架材料從傳統粉末推進至功能性連續薄膜平台。 本論文第一部分設計並製備 MOF-on-COF 異質雙層膜，用於離子選擇性傳輸與滲透能發電。首先藉由界面縮合反應製備自由支撐 COF 膜，再利用單側暴露策略於 COF 膜表面選擇性生長 UiO-66-NH2 MOF 層，成功建立具有孔徑與表面電荷不對稱性的異質膜結構。此設計結合 MOF 次奈米孔道所提供的離子篩分能力，以及 COF 連續孔道所帶來的離子傳輸路徑，使膜材料在濃度梯度下提升發電表現。進一步的陽離子與陰離子種類比較也顯示，MOF-on-COF 異質膜可展現高離子選擇性，並有效區分不同水合尺寸與電荷特性的離子；其整體滲透能轉換行為主要受到水合離子尺寸、離子電荷、孔徑限制與界面不對稱性等因素共同調控。 第二部分則發展溶劑揮發誘導組裝法，以 block copolymer 作為軟模板，製備連續中孔無定形 ZIF-90 薄膜。透過調控 THF/MeOH 共溶劑環境、配體濃度、微胞形成與快速溶劑揮發過程，本研究成功抑制 ZIF-90 在薄膜形成過程中的結晶行為，同時引入可連通的中孔結構。結構分析顯示，所得 aZIF-90 薄膜具有連續形貌、均勻孔洞分布與保留的 Zn–imidazolate 配位環境。進一步地，本研究亦透過理論計算探討不同溶劑環境對 ICA 去質子化與 Zn(II) 配位交換行為的影響，試圖從熱力學角度理解 THF-rich 條件下 ZIF-90 前驅物較容易維持於無定形狀態的原因。因此，本研究將無定形相作為一種有效的相態工程策略，用以避免晶粒邊界與不連續顆粒生成。進一步以尿酸電化學感測作為概念驗證，證明中孔無定形結構可改善分子擴散與活性位點可及性。 整體而言，本論文展示了結構設計與相態工程在多孔骨架薄膜材料中的重要性。透過結晶 MOF/COF 異質介面與溶劑揮發誘導之中孔無定形 MOF 薄膜，本研究提供了建構連續多孔框架薄膜的新策略，並為未來能源轉換、離子傳輸與電化學感測應用提供重要的材料設計方向。

Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as important porous material platforms because of their highly designable pore structures, large surface areas, tunable surface chemistry, and diverse framework compositions. However, conventional MOFs and COFs are mostly synthesized and investigated in powder form, which still presents several limitations for practical device applications, including poor film continuity, increased interparticle transport resistance, weak interfacial contact, and discontinuous pore pathways. These issues are particularly critical for ion transport, osmotic power generation, and electrochemical sensing, where porous materials must not only possess intrinsic pore functions but also be constructed into continuous and controllable thin-film or membrane architectures. Therefore, this dissertation focuses on the phase engineering and structural design of porous framework thin films, aiming to advance porous framework materials from conventional powders toward functional continuous thin-film platforms through heterointerface design and mesoporous amorphous film construction. In the first part, a MOF-on-COF heterogeneous bilayer membrane was designed and fabricated for ion-selective transport and osmotic power generation. A free-standing COF membrane was first prepared through interfacial condensation synthesis, followed by the selective growth of a UiO-66-NH2 MOF layer on one side of the COF membrane using a one-sided exposure strategy. This design successfully produced a heterostructured membrane with asymmetric pore sizes and surface charges. The MOF layer provides sub-nanometer channels for ion sieving, while the COF layer offers continuous ion-transport pathways, leading to enhanced power generation under concentration gradients. Further comparison of different cation and anion systems revealed that the MOF-on-COF membrane exhibits high ion selectivity and can effectively distinguish ions with different hydrated sizes and charge properties. The overall osmotic energy conversion behavior is jointly regulated by hydrated ion size, ion charge, pore confinement, and interfacial asymmetry. In the second part, a solvent evaporation-induced assembly strategy was developed to prepare continuous mesoporous amorphous ZIF-90 thin films using a block copolymer as a soft template. By controlling the THF/MeOH co-solvent environment, ligand concentration, micelle formation, and the rapid solvent evaporation process, ZIF-90 crystallization during film formation was successfully suppressed while interconnected mesopores were introduced. Structural analyses confirmed that the resulting aZIF-90 films exhibit continuous morphology, uniform pore distribution, and retained Zn–imidazolate coordination environments. In addition, theoretical calculations were used to investigate the influence of solvent environment on ICA deprotonation and Zn(II) ligand-exchange behavior, providing a thermodynamic understanding of why ZIF-90 precursors can more easily remain in an amorphous state under THF-rich conditions. Therefore, the amorphous phase is employed in this work as an effective phase-engineering strategy to avoid grain boundaries and discontinuous particle formation. As a proof-of-concept application, uric acid electrochemical sensing further demonstrated that the mesoporous amorphous structure can improve molecular diffusion and active-site accessibility. Overall, this dissertation highlights the importance of structural design and phase engineering in porous framework thin films. Through crystalline MOF/COF heterointerfaces and solvent evaporation-induced mesoporous amorphous MOF films, this work provides new strategies for constructing continuous porous framework thin films and offers useful material design principles for future applications in energy conversion, ion transport, and electrochemical sensing.