取代基苯胺對苯胺膜電致色變的影響

Abstract

本研究主要目地在研究改進以聚苯胺系列高分子與高分子電解質所構成電 致色變元件的循環壽命及特性.研究中使用 o-Anisidine 與 2-Fluoroaniline,o-AminobenzotrifluorideAnthranilonitrile,1/2 電 化學共聚合於 ITO 導電玻璃上為電致色變材料(工作電極);經附上對電極 薄膜的 ITO 玻璃為對電極;中間疊合 PAA/PEC 與 PEC/LiClO4 所形成的 高分子電解質層,構成電致色變元件.循環伏安法研究顯示此三種電化學共 聚合薄膜與 o-Anisidine 單獨電化學聚合之 poly(o-anisidine)電化學 特性類似,皆為第一步電子轉移反應形成自由基離子(由淡黃色變成綠色) 第二步電子轉移伴隨質子的得失形成氮原子的 sp2 結構(由綠色變為藍紫 色).但其電化學特性參數△E1/2則不相同.o-Anisidine 與 2-Fluoroaniline,o-Aminobenzotrifluoride,Anthranilontrile 1/2 電 化學共聚合於 ITO 上其 △E1/2 分別為 442 mV,425.5mV,465mV(CV測試, 以白金為對電極,於 1N HCl 掃描速度 5mV/s,相對於 SCE),對應鹼性態苯 胺紫外可見光光譜的第一吸收峰波長 340 nm,318 nm,359 nm,則顯示出共 聚合造成高分子主鏈間的立體效應 o-Aminobenzotrifluoride 大於 2-Fluoroaniline 大於 Anthranilonitrile元件電致色變循環壽命測試, 顯示與主鏈間立體效應相同趨勢,o-Aminobenzotrifluoride~4500次大於 2-Fluoroaniline~4000次大於 Anthranilonitrile~2000次.此結果亦表示 出聚苯胺主鏈間立體效應與循環壽命正比的關係.而 o-Anisidine 與 o- Aminobenzotrifluo-ride 1/2 電化學共聚合之電致色變元件循環壽命可 高達~5500次. A series of electrochromic polymers were electropolymerized from varioussubstituted anilines with one component or two components. The substitutedanilines included o-anisidine, o- aminobenzotrifluoride, anthranilonitrile,and 2-fluoroaniline. In the cyclic voltammetry(CV) study, poly(o-anisidine)and o- anisidine copolymer had the same electron transfer reaction : (1)withthe formation of semiquinone radical cation (color from pale yellow to green),(2)with the formation of sp2 hybrid in nitrogen atoms by deportonation (colorfrom green to purple- blue).However, the electrochemical parameters, △E1/2, were different for these co-polymers. The values of △E1/2 were 425.5 mV, 442 mV, 465 mV for o-anisidine/ o-aminobenzotrifluoride, o- anisidine / 2-fluoroaniline, and o-anisidine / anthranilonitrile copolymers respectively at a molar ratio of 1/2. The UV- VISspectra for the base form of these polyaniline copolymers also confirmed the order of the feasibility of electrochemical reaction as follows : o-aminobenzo-trifluoride > 2-fluoroaniline > anthranilonitrile.The electrochromic device was composed of an ITO glass as a counter electrode,a polymer electrolyte layer, and a polyaniline copolymer deposited on the otherITO glass as a working electrode. The polymer electrolyte, being made of poly( acrylic acid)( PAA ), chlorine terminated poly(ethylene ether)( PEC ), and PEC/LiClO4 polymer solution, was sandwiched between the two electrodes to form an electrochromic device. It has been observed that the cyclic life of the electro-chromic device increased with the bulk of the substituted groups of the poly- anilines. The cyclic life was of 4500 cycles for o- aminobenzotrifluoride copolymer system longer than that of the 2-fluoroaniline system (around 4000cycles), and the cyclic life of anthranilonitrile copolymer system was of 2000cycles. A longer cyclic life of 5500 cycles for o-anisidine / o- aminobenzotri-fluoride electrochromic system could also be obtained by designing a specialcounter electrode.