製備樹枝狀共聚物及其在形態之影響

Abstract

本論文中，主要是探討樹枝狀共聚物(dendritic block copolymers)的自組裝行為，並且藉由改變樹枝狀共聚物的兩崁鏈段中組成與構型，並進一步進行形態上的觀察，製備具備反應選擇性官能基(azetidine-2,4-dione)為建構單元，並製備不同代數的樹枝狀分子，並經由FT-IR、1H-NMR、EA、MASS的結構鑑定，判定其結構的正確性。並導入軟鏈段製備樹枝狀共聚物，增加兩崁鏈段的作用力參數，調控不同代數的樹枝狀分子、改變軟鏈段長度與分子構形分別製備線型與啞鈴型樹枝狀共聚物，並藉由FT-IR、1H-NMR、EA、MASS及GPC的結構鑑定。 由於樹枝狀分子因為代數越高，其分支情形越明顯，不利於結晶排列，然而樹枝狀共聚物藉由兩崁鏈段的作用力差異進行自組裝排列，其中L1D0BC的Tm為20 oC, 60 oC，隨著代數的增加，反而誘導高代數的樹枝狀共聚物能沿著兩崁鏈段的界面進行結晶排列，因此，L1D2BC的Tm提升到37 oC, 86 oC。利用TEM觀察自組裝行為在形態上的變化，樹枝狀共聚物，以L1D0BC為例，其自組裝成層狀，間距為30 nm，隨著代數的增加，結構形態轉變為蟲狀再轉變成球狀，並經由SAXS與Igor軟體進行高分子擬合佐證，而當軟鏈段的鏈長增加時，其中L2D0BC自組裝成圓柱狀，且圓柱的半徑為6 nm，間距為21.2 nm，此外當改變樹枝狀共聚物的分子構形時，D2D0BC則是又轉為層狀，間距為30 nm，因此可以藉由不同代數的樹枝狀分子、改變軟鏈段長度與分子構形來操控樹枝狀共聚物的形態。

This work consists of the synthesis of dendritic block copolymers (DBCs) with various flexible chain lengths, architectures and numbers of branching generations, and the effects of these structural factors on the morphologies. A series of poly(urethane/malonamide)dendrons were synthesized first based on the reactive building block, 4-isocyanate-4-(3,3-dimethyl-2,4-dioxo-azetidine)-diphenylmethane (IDD) with different numbers of branching generations. All the dendrons were confirmed by FT-IR, 1H-NMR, EA and Mass. Subsequently, the flexible poly(oxyalkylene) reacted with the reactive dendrons with different numbers of branching generations. Hence, several series of DBCs were synthesized and confirmed by FT-IR, 1H-NMR and GPC. Because the high branching generations of dendrons were difficult to self-assemble, a soft segment was incorporated to enhance the x values of DBCs. As a result, the presence of microphase separation between the interface would certainly induce a pattern of the architecture of dendrons with high branching generations to self-assemble. In addition, two melting transitions, pertaining to the partial micro-separation were observed as measured by DSC. In the L1DBC system, Tm1 and Tm2 were increased from 20 oC, 60 oC to 37 oC, 86 oC, respectively, when a dendron of higher generation was incorporated onto a DBC. The TEM image of L1DBC showed the morphologies were lamellar, worm-like and sphere, dependent on increasing generation of dendrons in L1DBCs accordingly. Furthermore, the morpholgy of L2D0BC and D2D0BC were cylinder and lamellar by the extension of flexible chain lengths and architecture conformation, respectively. All the DBCs were confirmed by Small angle x-ray scattering (SAXS) and Igor software curve fitting.