共軛發光高分子之合成及應用

Abstract

第一部份 含硫烷基側鏈PPV衍生物之合成及光學性質研究本論文合成了兩個 含硫烷基側鏈的PPV衍生物：Poly[2-methoxy-5-(2-ethylhexylthio)-p-phenylenevinylene] (S-PPV )及Poly[2-methylthio-5-(2-thylhexylthio)-p-phenylenevinylene] (SS-PPV )。加熱可溶於1,2-diclorobenzene。 由於硫原子的體積大於氧，立體障礙造成有效共軛長度下降，使得具有硫烷基長側鏈取代的S-PPV較MEH-PPV的螢光放射波長藍位移約40nm。而SS-PPV由於含有兩個硫烷基側鏈的取代，使得其立體障礙降低，且硫烷基提供電子能力大於氧烷基，造成螢光放射波長較S-PPV紅位移約20nm。 而在溶劑效應方面，因為1,2-diclorobenzene的沸點遠大於THF，所以溶劑揮發度較小，造成較厚的高分子薄膜，高分子主鏈此時有較多的時間形成熱力學穩定的構形。高分子主鏈彼此間形成纏繞，進而產生強的堆疊，造成PL放射波長比使用THF當溶劑時，產生紅位移的現象。 第二部份 螢光共軛高分子應用於TNT化學偵檢器之研究 近年來，在化學、生物及製藥科學領域，有機螢光偵檢器一直是個很重要的研究課題。而共軛高分子獨特的電子特性，使其能成為一化學偵檢器很好的材料。在固體薄膜狀況下，共軛高分子展現出其獨特的光學性質，能夠應用在有機發光二極體、薄膜電晶體、太陽能電池及化學偵檢器上。繞曲性、製程容易、具有半導體及其它特別的光電性質是共軛高分子最吸引人的特性。 本論文使用chlorine precursor route (CPR)的方法，合成了受到廣泛討論的兩個螢光物質poly[2-methoxy-5-(( 2-ethylhexyl)-oxy)-p-phenylenevinylene] (MEH-PPV)及poly (2.3-diphenyl-5-n-decyl- p-phenylenevinylene) (DP10-PPV) 。另外也得到另一個具有強螢光特性的高分子poly [1-(p-n-butylphenyl)-2-phenylacetylene] (PDPA-nBu) 。使用這三個高分子，對於TNT、2.4-dinitrotolunene(2.4-DNT) 、2.6-dinitrotolunene (2.6-DNT) 及p-nitrotoluene(4-NT)的蒸氣有很好的螢光化學偵檢器的功效。

PART 1 Syntheses and Optical properties of Alkylthio Side Chain Poly(p-pheneylenevinylene) Poly[2-methoxy-5-(2-ethylhexylthio)-p-phenylenevinylene] (S-PPV ) and Poly[2-methylthio-5-(2-ethylhexylthio)-p-phenylenevinylene] (SS-PPV ) were synthesized in this films via Gilch polymerization and were soluble in hot 1,2-diclorobenzene. The S-PPV was blue-shifted absorption and emission compared to those of MEH-PPV.The reason is that the bulky alkylthio group in the phenylene ring diminishes the conjugation length over the polymer chain rather than donates electron to the polymer backbone. The photoluminescence of SS-PPV indicated Red-shifted absorption and emission compared to S-PPV because two alkylthio group reduced steric hindrance and increased donates electron ability. In solvent effect. It is expected that slow evaporation of the solvent(and thus a slow increase of the polymer concentration within the film) should favor the entanglement of the polymer chains and the formation of stronger aggregates. Therefore, the PL red-shift effect was observed in 1,2-diclorobenzene. PART2 Fluorescent Conjugated Polymer Films as TNT Chemosensors The development of fluorescent sensors for organic molecules is of great practical importance in chemical, biological, and pharmaceutical sciences(1-3). Indeed the electronic properties of conjugated polymer films provide unique opportunities for the formation of chemosensory materials(4).Among the condensed systems on the solid surface, conjugated polymers also exhibit unusual photophysical properties and have considerable interest because of their potential application, such as organic light emitting diodes(5)、thin film transistors(6)、solar cells(7) and chemosensors(8). The flexibility, ease of processing, semiconducting and interesting optical properties are the most attractive characteristics of conjugated polymers. We report herein an approach to preaper poly[2-methoxy-5-((2-ethylhexyl)-oxy)-p-phenylenevinylene](MEH-PPV) (9) and poly(2.3-diphenyl-5-n-decyl-p-phenylenevinylene) (DP10-PPV) (10) via a chlorine precursor route (CPR) (11),which were widely studied active luminescent materials . Additionally we have synthesized poly[1-(p-n-butylphenyl)-2-phenylacetylene] (PDPA-nBu) (12), which were the strong luminescent disubstituted polyacetylene (PA). Moreover, their potential for the trace detection of high explosives such as 2.4.6-trinitrotulene (TNT) is also reported (13) polymers have high sensitivity as an artificial fluorescent chemosensor for the vapors of TNT, 2.4-dinitrotolunene (2.4-DNT) , 2.6-dinitrotolunene(2.6-DNT) and p-nitrotoluene(4-NT)