【摘要】：隨著全球能源的急劇消耗和環(huán)境的不斷惡化,節(jié)能環(huán)保材料吸引了人們的廣泛關注。電致變色材料正是這樣一種可以改變人類生活方式并且有助于合理利用能源的新型功能材料。導電聚合物因結構易修飾、著色效率較高、響應時間較短、光學對比度較高及較豐富的顏色變換而成為電致變色材料中最具有潛力的一類物質。導電聚合物電致變色機理是基于聚合物的氧化還原與離子的摻雜與脫摻雜兩個過程,而這樣兩個過程與聚合物的結構有著非常密切的關系。本論文通過合理的分子結構設計得到具有不同分子構型的單體,通過電化學聚合構筑一系列具有不同交聯(lián)結構的噻吩類電致變色聚合物,探究單體分子構型-聚合物交聯(lián)結構-電致變色性質之間的關系。本論文第一部分通過引入不同個數(shù)的苯至噻吩-吡咯-噻吩結構中,形成了中間以苯為橋、外圍具有四個噻吩單元的新型單體(PhSNS,BPhSNS,TPhSNS),經電化學形成了交聯(lián)結構的聚合物。由于橋鍵單元苯環(huán)個數(shù)的變化即橋鍵空間位阻大小的變化,使得三種單體可能具有不同的分子構型,從而可能導致聚合物表現(xiàn)不同的交聯(lián)結構。單體循環(huán)伏安曲線表明,相比TPhSNS和BPhSNS,PhSNS具有兩個氧化還原峰,量子化學分析證實這可能主要是PhSNS和BPhSNS、TPhSNS具有不同的分子構型,PhSNS單體的兩條噻吩-吡咯-噻吩結構中噻吩和吡咯的扭曲角不相同(21.2°,40.2°),而BPhSNS、TPhSNS兩條噻吩-吡咯-噻吩都具有相同的扭曲角(22.4°),這使得前者和后兩者具有不同的電化學和光學性質。由于三個單體具有相似的起始氧化還原電位及三個單體的聚合物薄膜具有相似的氧化還原曲線,使得其相應的聚合物薄膜具有相似的多色變色行為(黃色-灰綠色-灰色),聚合物薄膜pPhSNS、pBPhSNS在1100 nm處的對比度為40%左右,著色時間和褪色時間為1 s左右,但由于TPhSNS結構中三聯(lián)苯強的剛性使得其具有差的溶解性,從而導致相應的聚合物薄膜pTPhSNS具有相對較差的電致變色性質。但是,TPhSNS通過與EDOT進行共聚,發(fā)現(xiàn)共聚物pTPhSNS-EDOT相比均聚物pTPhSNS薄膜電致變色性能具有很大的改善,表現(xiàn)出合理的光學對比度40%(1100 nm)、快速的響應速度0.37 s(1100 nm)及良好的電化學穩(wěn)定性等,這可能是因為引入柔性結構的EDOT結構至pTPhSNS聚合物形成了想要的交聯(lián)結構聚合物薄膜。本論文第二部分通過引入不同個數(shù)苯至噻吩-咔唑-噻吩結構單元中,同樣形成了外圍具有四個噻吩的新型結構單體(BTCPh,BTCBPh),多位點的單體經電化學聚合之后形成了交聯(lián)結構聚合物薄膜,同樣由于中心苯環(huán)個數(shù)及空間位阻的變化,導致單體具有不同的分子構型,導致形成不同的交聯(lián)結構聚合物。單體循環(huán)伏安曲線、紫外光譜分析證明兩個單體具有相似的電化學及光學性質,聚合物薄膜pBTCPh、pBTCBPh同樣表現(xiàn)出相似的氧化還原曲線,這使得兩種聚合物薄膜具有相似的光譜電化學性質,且有相似的變色行為。動力學結果表明,聚合物薄膜pBTCPh和pBTCBP表現(xiàn)出相似的光學對比度,在410 nm、660、1100nm的光學對比度分別為25%、40%、50%。從電致變色響應時間來看,pBTCPh薄膜相比pBTCBPh具有更快的響應速度,特別是在660 nm,前者的響應時間為后者的一半,從掃描電鏡圖譜來看,這可能是由于pBTCPh薄膜相比pBTCBPh具有更加疏松的顆粒堆積方式,有利于電致變色過程中離子的嵌入與脫出過程,從而導致前者比后者響應速度更快。此外,從電致變色過程中電荷注入行為來看,pBTCPh相比pBTCBPh具有更加快速的電荷注入能力,同樣能夠加快電致變色的響應。本論文第三部分以四苯基甲烷為中心結構單元,通過still偶聯(lián)在四個苯單元接入不同數(shù)目的噻吩單元形成新的單體結構(TPhTTh、TPhTBTh、TPhBTThBBr),由于外圍結構同樣為四個噻吩單元,經電聚合也能夠形成交聯(lián)結構的聚合物。由于四苯基甲烷中心原子碳為sp_3雜化,單體經電化學聚合形成的聚合物共軛長度是可控的,因此本部分將還將研究不同共軛長度對電致變色性能的影響。三個單體的循環(huán)伏安曲線、量子化學計算分析及紫外光譜表明,隨著外圍噻吩數(shù)目的增加,單體的共軛水平也隨著增加,同時其紫外光譜發(fā)生相應的紅移,起始氧化電位更低。從三個單體的電化學聚合中發(fā)現(xiàn),TPhTTh不能有效地成膜,TPhTBTh、TPhBTThBBr很好地沉積到ITO表明上,形成相應的聚合物薄膜pTPhTBTh、p TPhBTThBBr;聚合物薄膜的循環(huán)伏安及紫外光譜表明,pTPhBTThBBr具有更低的氧化電壓,且紅移40 nm,中性態(tài)為橙黃色。兩種聚合物薄膜的電化學光譜表明,后者具有更加明顯的光譜變化,同時后者具有更好的電致變色性質,高的光學對比度55%(1100 nm),快速的響應速度及良好的電化學穩(wěn)定性。從兩種薄膜的掃描電鏡表明,后者薄膜顯示出比較疏松的顆粒堆積形貌,這可能是導致后者電致變色性能好的重要原因。此外,pTPhBTThBBr薄膜相比pTPhTBTh具有更好的共軛水平,這可能也是導致后者性能好的原因。
[Abstract]:With the rapid consumption of global energy and the deterioration of the environment, energy-saving and environmental protection materials have attracted wide attention. Electrochromic materials are a new type of functional materials which can change the way of human life and contribute to the rational use of energy. Conductive polymers are easy to modify their structures, have high coloring efficiency and short response time. The electrochromic mechanism of conducting polymers is based on the two processes of redox and ion doping and de-doping, which are closely related to the structure of polymers. A series of thiophene electrochromic polymers with different cross-linking structures were synthesized by electrochemical polymerization. The relationship between molecular configuration, cross-linking structure and electrochromic properties of thiophene was investigated. In the first part of this paper, different number of benzene was introduced. In the thiophene-pyrrole-thiophene structure, a new monomer (PhSNS, BPhSNS, TPhSNS) with four thiophene units was formed, which was bridged by benzene and electrochemically formed a crosslinked polymer. Compared with TPhSNS and BPhSNS, PhSNS has two redox peaks. Quantum chemical analysis shows that this may be mainly due to the different molecular configurations of PhSNS and BPhSNS, TPhSNS, and the thiophene and pyrrole thiophene in the two thiophene-pyrrole-thiophene structures of PhSNS. Both BPhSNS and TPhSNS have the same twist angle (22.4 degrees), which makes the former and the latter have different electrochemical and optical properties. The original curve makes the corresponding polymer film have similar polychromic behavior (yellow-grey-green-grey). The contrast of the polymer film pPhSNS and pBPhSNS is about 40% at 1100 nm, and the coloring time and fading time are about 1 s. However, due to the rigidity of the terphenyl in the structure of TPhSNS, the polymer film has poor solubility. However, by copolymerizing with EDOT, it was found that the electrochromic properties of the copolymer pTPhSNS-EDOT were greatly improved compared with that of the homopolymer pTPhSNS-EDOT, showing a reasonable optical contrast of 40% (1100 nm), a fast response speed of 0.37 s (1100 nm) and a good electrochromic property. In the second part of this paper, by introducing different number of benzene to thiophene-carbazole-thiophene structural units, a new monomer with four thiophenes (BTCPh, BTCBPh) was also formed. Polymer films with cross-linking structure were formed by electrochemical polymerization of monomers at different sites. Similarly, the number of central benzene rings and the change of steric hindrance lead to different molecular configurations of monomers, resulting in the formation of different cross-linking structure polymers. The similar redox curves of the polymer films, pBTCPh and pBTCBPh, result in similar spectroelectrochemical properties and similar discoloration behavior. Kinetic results show that pBTCPh and pBTCBP have similar optical contrast at 410 nm, 660, 1100 nm. From the electrochromic response time, the response time of pBTCPh film is faster than that of pBTCBPh, especially at 660 nm. The response time of pBTCPh film is half of that of pBTCBPh film. From the scanning electron microscopy (SEM), this may be because pBTCPh film has a more loose packing mode than that of pBTCBPh film, which is advantageous to the electrochromic response time. In addition, compared with pBTCBPh, pBTCPh has a faster charge injection ability and can also accelerate the electrochromic response. In the third part of this paper, tetraphenylmethane is used as the intermediate. A new monomer structure (TPhTTh, TPhTBTh, TPhBTThBBr) is formed by still coupling of four benzene units into thiophene units. Because the outer structure is also four thiophene units, a polymer with cross-linking structure can also be formed by electropolymerization. The conjugate lengths of polymers formed by chemical polymerization are controllable, so the effects of different conjugate lengths on the electrochromic properties will also be studied in this section. From the electrochemical polymerization of the three monomers, it was found that TPhTTh could not form films effectively. TPhTBTh and TPhBTThBBr were well deposited on ITO, and the corresponding polymer films pTPhTBTh and pTPhBTThBBr were formed. The cyclic voltammetry and ultraviolet spectra of the polymer films showed that pTPhBTThBBr was more effective. The electrochemical spectra of the two kinds of polymer films show that the latter has more obvious spectral changes, while the latter has better electrochromic properties, high optical contrast 55% (1100 nm), fast response speed and good electrochemical stability. Electron microscopy showed that the latter film exhibited a relatively loose packing morphology, which may be an important reason for the better electrochromic properties of the latter. In addition, the pTPhBTThBBr film has a better conjugation level than the pTPhTBTh film, which may also be the reason for the better properties of the latter.
【學位授予單位】：浙江工業(yè)大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O633.5

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