利用物質之自組裝行為製備功能性材料為目前新型材料研發上的重要趨勢之一。這類材料的 材料性質往往可透過自組裝結構的改變來加以調整。理論上，研發人員便可根據此一原則設 計出擁有所需材料性質的功能性材料。然而，了解自組裝行為如何受物質本身的化學結構、 外在環境因子及外力所影響，以及了解結構與性質之間的關聯性，仍然是基礎科學研究以及 新型材料開發上的一大挑戰。為促使”以化學式預測自組裝結構及材料性質”之最高目標的達 成，本項三年期計畫將以雙子型界面活性劑為研究標的物，以熱力學原則探討化學結構與自 組裝結構之關聯性。透過合成一系列擁有不同碳氫鏈長度或不同連結基長度之雙子型界面活 性劑，並對其進行堆疊參數的計算以及使用我們所開發的X 光散射/繞射技術測量其自發曲 率，我們可望建立「化學結構」、「堆疊參數」、「自發曲率」三者間的關聯性；利用自發曲率 與自組裝結構之自由能的相關性，我們甚至可在熱力學的原則下探討前述關聯性背後的物理 機制。同樣地，我們亦將分別利用蘭牟爾槽技術及上述之X 光散射/繞射技術測量雙子型界面 活性劑的分子間作用力與彎曲模數，以建立「化學結構」、「分子間作用力」、「彎曲模數」三 者間的關聯性。兩項關聯性及其背後物理機制的結合，將可使我們大幅往”以化學結構預測自 組裝行為”的目標邁進。 ;Exploiting the self-assembling behavior of molecules or group of molecules to fabricate functional materials has been driving many research efforts dedicating to developing novel materials. The material properties of such materials are tunable via modulating the dimensions and types of the self-assembled structures. In principle, one can apply this characteristic to design and fabricate functional materials with desired properties. Nevertheless, it is still a formidable scientific and technical challenge to predict from the chemical structure the self-assembling behavior of a substance under different external stimuli and at various environments, let alone predicting its material properties. To facilitate the realization of the ultimate goal, “predict self-assembled structures and the resultant material properties from the chemical formula of a substance”, this grant proposal presents a 3-year project where the correlations between chemical structure and self-assembling behavior will be thermodynamically investigated for series of to-be-synthesized gemini surfactants featured with different hydrocarbon chain lengths or spacer lengths. The packing parameters of the surfactants will be calculated while their spontaneous curvatures will be measured with our newly developed, X-ray scattering/diffraction-based technique, to explore the correlations among chemical structure, packing parameters and spontaneous curvature. Exploiting the thermodynamic relation of spontaneous curvature and free energy of a self-assembled structure, we would even uncover the physical mechanisms underlying the foregoing correlations. Correspondingly, the Langmuir trough and our X-ray-based techniques will be employed to determine the intermolecular interactions and bending moduli, respectively, of the gemini surfactants to explore the correlations among chemical structure, intermolecular interactions and bending modulus, and the physical mechanisms behind the correlations. The integration of the two types of correlations, along with their underlying physical mechanisms, would ultimately lead to the development of the predictive capability by which the self-assembling behavior of a substance is foreseeable from its chemical formula.
