新型共軛性聚電解質與導電性星狀高分子共聚物之合成與性質分析

Synthesis and Characterization of Novel Conjugated Polyelectrolytes and Electro-Active Starburst Block Copolymers

葉志富(Chih-Fu Yeh)

指導教授 ： 王立義

國立臺灣大學/工學院/高分子科學與工程學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.02335

摘要

自從在1977年發現聚乙炔導電高分子之後，由於導電高分子具有相當優異之光電特性，因此為學界與工業界的熱門研究項目之一；但由於導電高分子主鏈剛硬結構導致其材料性質剛硬且加工性質差，大大降低其應用上的價值。因此在本論文中，我們開發出三種方法來改善導電高分子之加工性質；首先，我們合成出一系列新型導電高分子─poly(3,4-propylenedioxythiophene) (PProDOT)衍生物，藉由在主鏈結構上以酯基鍵結的方式導入一長鏈分子，使其能溶於一般有機溶劑中；當導入一長鏈分子(C12)後，其在高溫時，碳鏈的擾動將會對分子鏈的排列上，造成破壞，導致其在UV-vis光譜上最大吸收波峰(λmax)會有藍位移的現象，因此具有應用於溫度感測器(temperature sensors)之應用價值。另外，我們在鹼性下水解將酯基基團切除，可得到水溶性相當高之導電高分子；由於水溶性聚電解質本身分子鏈上帶有許多電荷，因此在水溶液中，對於pH值的變化極其敏感，在UV-vis光譜，在不同pH值下，由於分子鏈構形之改變導致其共軛長度的改變，進而影響(λmax)的改變。在第二部分，我們利用核殼乳膠顆粒(core-shell latex)改質導電性高分子製程的概念，設計出單一分子型的導電核殼粒子，首先，我們製備出一星狀高分子─poly(n-butylacrylate) (PBA)為核心，並利用末端基改質使其帶有導電高分子的單體─噻吩(thiophene)，之後利用氧化聚合的方式，進行導電高分子鏈的成長；由於此一星狀共聚物之兩種不同成分高分子是以共價鍵所鍵結，且星狀高分子其特殊之3D構造且其尺度在奈米等級，因此，我們可將其視為一單分子似核殼型導電奈米粒子。此一似核殼型導電奈米粒子於有機溶劑中具有很高的溶解度，且保有原導電高分子之光電特性。在第三部分，我們結合了導電核殼粒子與交聯性高分子的概念，以末端基改質的方式，將三噻吩(terthiophene)分子修飾於星狀高分子(PBA)的尾端成為交聯型導電高分子的前趨物，之後將前趨物塗於基材上形成薄膜，再利用固態氧化交聯法以iron(III) chloride為氧化劑塗佈於前趨物的薄膜上，使其氧化聚合進而交聯形成導電薄膜。此法由於前趨物高分子具有溶解度高、加工性佳及與基材之附著性佳等特性，再藉由簡易的氧化聚合法，因此，可以在任何基材上形成一性質優良之導電薄膜。

關鍵字

共軛性聚電解質 ； 星狀高分子共聚物

並列摘要

Since the discovery of electrically conductive polyacetylene in 1977, conducting polymers have attracted considerable attention in academic fields and industrial secters due to their novel optoelectronic properties and apparent potential use in organic electronic devices. An important characteristics of conducting polymers is the conjugated π-system along their backbone, making them typically both fragile and rigid, which severely limits their practical uses. Here, we developed three stratgies to solve this problem. First, we synthesized various types of soluble poly(3,4-propylenedioxythiophene) (PProDOT) derivatives with a long alkyl side chain. The strong dependence of the change in their thermochromic property upon the insertion of long alkyl chain (C12) indicates that side-chain disordering increases their steric hindrance to adopt a nonplanar conformation at high temperatures. On the other hand, their corresponding water soluble conducting polyelectrolytes was hydrolyzed by NaOH(aq.) on the ester polymer precusors. When pH is decreased from 12.5 to 7, the λmax of PProDOT derivatives was blue shift in UV-vis absorption. The blue shift should be related to a transition from rigid-rod to a random-coil conformation of the PProDOT derivatives, as any twisting of the conjugated backbone leads to a decrease of the effective conjugation length. In the second part, we present a new approach for preparing stable conductive core-shell nanoparticles without any surfactants. This method includes synthesis of a starburst polymer via atom transfer radical polymerization (ATRP) of n-butylacrylate as a core using a multi-arm molecule, followed by the growth of conjugated segments from each chain-end of the star polymer to yield a dendritic block copolymer. Atomic force microscopic (AFM) images clearly indicate that these polymers form unimolecular spherical nanoparticles with a well-defined core-shell structure. In the third part, a novel conductive polymer composite with core-shell-like nanostructure was successfully synthesized using 12-armed terthiophene-terminated starburst poly(n-butylacrylate) as precursor. Solid-state coupling among terthienyl groups on the chain-ends of the star polymer can be effectively performed by simple oxidative polymerization using FeCl3 as an oxidant to yield a three-dimensional network of oligoterthiophene. The unique core-shell-like structure enables the composite film to possess good conductivity at very low conjugated moiety content. Furthermore, the use of elastomeric poly(n-butylacrylate) (PBA) as core in the star growth core-shell polymer allows the preparation of a uniform and large-area conductive thin film with notable flexibility and excellent adhesion to a wide variety of substrates.

並列關鍵字

conjugated polyelectrolytes ； starburst block copolymer

參考文獻

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