利用速配接合反應合成兩性之剛硬/柔軟雙嵌段式共聚物DEH-PPV-b-PEO及其特性研究

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The self-assembly of block copolymers into nanostructure with novel morphology and property has attracted an increasing interest as a new approach for nanotechnology. In particular, block copolymers containing conducting polymer segments such as poly (phenylene vinylene) (PPV) are technologically important since PPVs are promising material for applications in low cost, large area and flexible organic optoelectronics. In this thesis, I described a novel method to synthesize poly(2,5-di(2’-ethylhexyloxy)-1-4-phenylenevinylene)-b-poly(ethylene oxide) (DEH-PPV-b-PEO) block copolymers via a coupling reaction of end-functionalized polymer building blocks such as 1,3-dipolar cycloaddition reaction between an alkyne terminated DEH-PPV and an azide terminated PEO. Aldehyde terminated monodispersed DEH-PPV homopolymers were synthesized using Siegrist polycondensation of 2,5-di(2”-ethylhexyloxy)-4’-methyl-N-benzylideneaniline and subsequently substitution of the terminal imino group with acid. Alkyne terminated PPV was obtained by reaction of aldehyde terminated PPV with propargyl bromide. Azide terminated PEO were synthesized by tosylation of the hydroxyl functionality of poly(ethylene glycol) methyl ether and subsequent substitution with sodium azide. The synthesized PPV-b-PEO block copolymers were characterized by various techniques including GPC, NMR, DSC, TGA, solution UV-Vis and PL. The microstructure and domain spacing for the synthesized block copolymers were further examined using small-angle x-ray scattering technique (SAXS). These block copolymers microphase separate and self-assemble into nanostructures of lamellae irrespective to the different PEO fractions, indicating the rod nature of PPV block. PPV-b-PEO shows significant solvatochromic transformation in different solvent/non-solvent mixture. The optical property of the PPV-b-PEO solution can be explained on the basis of aggregation, agglomeration, and collapse of isolated chains of PPV as well as the micelle and inverse micelle structures of PPV-b-PEO. The synthesis of PPV-b-PEO opens up the opportunity to study amphiphilic rod-coil block copolymers for future application.