簡易構建金屬-超分子雙嵌段共聚物及其自組裝研究

Abstract

在過去幾十年中，超分子化學在高分子中領域中以非共價鍵作用力控制其自組裝的行為引起了極大的關注。其中，超分子嵌段共聚物的自組裝行為除了受嵌段的組成和結構影響可形成複雜且多樣的形態外，超分子作用力的動態特性的引入給予了自組裝結構進一步重組或修飾的可能性。基於這個目標，開發高效的超分子嵌段共聚物的合成及其自組裝行為是本論文的主軸。 在這份研究中，通過精準地在高分子鏈末端分別引入了聯三吡啶和6,6'位點以蒽基修飾的聯三吡啶之互補配體，可以實現金屬-超分子雙嵌段共聚物。藉由可控聚合的方法合成了P3HT及PS，並將互補的聯三吡啶配體修飾到高分子鏈的末端。其中在PS的合成中，利用原子轉移自由基聚合使用了含有tpy-Fe錯合物的起始劑成功合成出不同分子量且末端具有tpy配基的PS。進一步構建以P3HT為硬段的金屬-超分子軟-硬雙嵌段共聚物[P3HT-b-PEO]及[P3HT-b-PS]，並研究其在溶液及薄膜中的自組裝形態。引入配體的互補性使得嵌段共聚物的製備更簡單，更有效，有利於合成具有各種嵌段比的嵌段共聚物，並使我們能夠更系統地研究嵌段共聚物的自組裝行為。 超分子作用力的動態特徵在自組裝的形態中，可以通過嵌段之間的斷開，使其結構上可以再進一步修飾。在[P3HT-b-PEO]的溶液中，可觀察到通過不同的軟硬嵌段比可調節其球狀與纖維狀的奈米結構。在其纖維狀奈米結構中，兩嵌段之間的鍵結可以透過TEA-EDTA斷開並選擇性除去PEO嵌段而證明其核-殼納米的結構。另一方面通過將[P3HT-b-PEO]的溶液滴加在基板上並置於磁場中緩慢揮發乾燥來進行排列而得到大面積排列[P3HT-b-PEO]的薄膜，此薄膜具有非等向性的吸光性及導電性。其中PEO嵌段也可利用TEA-EDTA選擇性的除去，可保留其規整的P3HT並消除了光電導度的非等向性。以互補的聯三吡啶配體的引入使得金屬-超分子軟-硬雙嵌段共聚物的合成更加簡便，從而能更快的合成各種嵌段比的嵌段共聚物，使得有系統的對不同嵌段比共聚物對其性質影響的趨勢研究可以更有效率。

In the past decades, the supramolecular chemistry in polymer science have realized in controlling self-assembly behaviors via non-covalent interaction and attracting huge attention. Among this field, the self-assembly behaviors of supramolecular block copolymer influenced by the intrinsic properties and length ratio between blocks lead to complex and diverse morphologies. Moreover, the dynamic feature of non-covalent connections endows the opportunity for further rearrangement and modification to yield well-defined assemblies. Therefore, developing facile synthetic strategies of well-defined supramolecular block copolymers and their self-assembly behavior is the main axis of this thesis. In the study, the facile construction of metallo-supramolecular diblock copolymers was achieved by the complementary complexation of well-defined polymers end-functionalized with 2,2':6',2'-terpyridine (tpy) and 6,6'-anthracenyl substituted tpy in the presence of ZnII ion. With the aspect of controlled/living polymerization, the synthetic polymers with high fidelity in the chain-end functionality was realized in poly(3-hexylthiophene) (P3HT) and polystyrene (PS). Among the preparation, tpy metallo-intiator was utilized in atom transfer radical polymerization (ATRP) of tpy-functionalized PS with various molecular weight. The introduction of complementary terpyridine complex makes the block copolymer preparation simpler and more efficient to afford a series of block copolymers with various block ratios, and allows us to further investigate the trend of block copolymers properties more systematically. The dynamic feature of non-covalent interaction in the self-assembled morphologies provide a possibility to rearrange and modify into well-defined assembly via dissociation of the junction between blocks. The self-assembled core-shell nanostructures of [P3HT-b-PEO] that could be tuned by varying block ratios in selected solution have been proved by the dissociation of the supramolecular linkage residing at the junction between two polymer blocks. In addition, magnetic field induced macroscopic alignment of [P3HT-b-PEO] film influenced by the self-assembled nanostructures of polymers in solution can be achieved during solvent evaporation in a 9 T magnetic field. The oriented polymer film revealed anisotropic optical property and photoconductivity, where selective removal of insulating PEO can be achieved by using TEA-EDTA and results retaining orientational P3HT domain but absence of anisotropic photoconductivity. The introduction of complementary complexation makes the synthesis of block copolymers with various block ratios easier, benefiting to the systematically study more efficient.