本文選題：碳納米管 + 功能化�。� 參考：《華東師范大學》2015年碩士論文

【摘要】：經(jīng)過二十多年的發(fā)展,碳納米管(Carbon Nanotubes, CNTs)領域己進入到應用化研究階段,制備具有實用價值的功能性CNTs材料是目前的主要研究方向。很多實際應用要求CNTs同時具備兩個條件：結構完整和功能化。因此,非破壞性的高效功能化是研究人員持續(xù)追求的一個目標。共價功能化通過CNTs和化學物質(zhì)反應形成共價鍵,能達到高功能化程度,但唯一的缺點是反應物攻擊CNTs管壁的C=C鍵,破壞CNTs的共軛結構。非共價功能化能在保持CNTs原有的結構的情況下引入官能團,但由于是基于CNTs與修飾劑分子的弱相互作用,其功能化程度一般不高,復合物也不穩(wěn)定。為了實現(xiàn)CNTs的非破壞性高效功能化及其相關應用,本論文做了以下工作。1.高分子對CNTs的非共價纏繞及其對染料分子的增強吸附(1)利用聚苯乙烯磺酸鈉(PSS)對CNTs的非共價纏繞,實現(xiàn)了對CNTs的非破壞性高效功能化,并研究了CNTs和PSS的相互作用。PSS具有柔性的分子鏈、豐富的陰離子基團和芳香側基,能通過非共價的纏繞為CNTs同時引入大量的負電荷和π電子。本實驗采用簡單的超聲分散和加熱攪拌的方法來制備CNT/PSS復合材料；產(chǎn)物的膠體分散性、紫外可見吸收光譜、紅外光譜(IR)、場發(fā)射掃描電鏡(FESEM)和熱重分析等結果證明了有大量的PSS修飾在了CNTs上。通過X一光電子能譜(XPS)對CNTs、PSS和CNT/PSS的化學狀態(tài)進行了表征,發(fā)現(xiàn)PSS的芳香側基和CNTs表面的共軛系統(tǒng)通過π-π作用結合在一起;同時PSS苯環(huán)上的強吸電子取代基磺酸基能夠利用這種π-π作用從CNTs上吸取電子,增加了磺基的電子云密度。據(jù)此,我們首次提出了CNTs和高分子可能通過“π-π電子供受”作用結合在一起的非共價修飾機理,而非簡單的π-π作用。(2)應用CNT/PSS實現(xiàn)了對染料分子的增強吸附,并研究了吸附機理。以亞甲基藍(MB)為模型吸附質(zhì),使用吸附等溫線和吸附動力學對比研究了CNTs和CNT/PSS的吸附行為。結果發(fā)現(xiàn),與未處理CNTs相比,CNT/PSS對MB的吸附速率和吸附容量卻有大大的提高,其中吸附容量為原來的2倍多,達到了100 mg/g,且在實驗條件下CNT/PSS用作吸附劑僅需3 min就能接近吸附平衡(CNTs需要10 min)。為了研究增強吸附的機理,使用XPS對吸附相互作用進行了表征。首先精確的定位了吸附位點(活性官能團),發(fā)現(xiàn)MB除了通過芳香環(huán)與CNTs管壁的π-π作用被吸附之外,還通過一端的二甲胺基被CNT/PSS表面的磺酸基靜電吸引；然后計算出了靜電作用和π-π作用對吸附容量的相對貢獻是2：1；并從分子構型等角度對靜電吸附的優(yōu)勢給予了合理解釋,最后使用理論計算證實了分析結果。2.六價鐵Fe(VI)用作CNTs的氧化劑及CNTs非破壞性共價功能化的實現(xiàn)首次使用高鐵酸鉀K2FeⅥO4作為CNTs的氧化劑,發(fā)現(xiàn)以濃硫酸為反應介質(zhì)時,Fe(Ⅵ)可在溫和的反應條件(60℃)下實現(xiàn)CNTs的快速(3h)羧基化,氧化效果通過了膠體分散性和IR的定性表征。這種新型的氧化方法具有反應條件溫和、高效、不產(chǎn)生污染物(唯一副產(chǎn)物是Fe3+)等優(yōu)點。更重要的是,該氧化手段不會破壞CNTs的共軛結構。用Raman光譜定量測試了氧化前后CNTs的缺陷程度,發(fā)現(xiàn)Fe(Ⅵ)的氧化不會在CNTs表面引入新的缺陷。結合Raman光譜、FESEM和XPS數(shù)據(jù),我們分析了氧化機理,結果表明：Fe(Ⅵ)對CNTs的氧化反應選擇性的發(fā)生在原有的sp3-C上,而不會破壞C=C鍵。CNTs外表面的sp3-C于3 h之內(nèi)被全部氧化,此時反應結束,延長反應至6 h并不會增加反應程度。由于非破壞性的氧化既引入了含氧官能團,又不破壞CNTs的結構,氧化的CNTs的產(chǎn)率超過了100wt%。用當前盛行的高效但具有破壞性的混酸(HNO3/H2SO4)氧化的結果與Fe(Ⅵ)氧化的結果進行了對比,進一步說明了Fe(Ⅵ)對CNTs的缺陷專一性/非破壞性的氧化機理。這種非破壞性氧化為CNTs的非破壞性共價功能化奠定了基礎。
[Abstract]:After more than 20 years of development, the Carbon Nanotubes (CNTs) field has entered the applied research stage. The preparation of functional CNTs materials with practical value is the main research direction. Many practical applications require that CNTs has two conditions at the same time: structural finishing and functionalization. Therefore, non destructive and efficient functionalization. It is a goal that researchers continue to pursue. Covalently functionalized through the reaction of CNTs and chemicals to form covalent bonds to achieve a high degree of function, but the only disadvantage is that the reactants attack the C=C key of the CNTs tube wall and destroy the conjugate structure of the CNTs. The non covalent functionalization can introduce functional groups in the case of maintaining the original structure of CNTs, but Therefore, based on the weak interaction of CNTs and modifier molecules, the degree of functionalization is generally low and the complex is not stable. In order to realize the nondestructive and efficient functionalization of CNTs and its related applications, the following work has been done by.1. polymer on the non covalent entanglement of CNTs and the enhanced adsorption of the dye molecules (1) using polystyrene sulfonic acid. The non covalent entanglement of CNTs by sodium (PSS) realizes non destructive and efficient functionalization of CNTs, and studies the interaction of CNTs and PSS with a flexible molecular chain, rich anionic groups and aromatic side groups. A large number of negative charges and pion electrons can be introduced into CNTs by non covalent entanglement, and a simple ultrasonic dispersion is used in this experiment. The CNT/PSS composite was prepared by the method of heating and stirring. The colloid dispersion, UV visible absorption spectrum, infrared spectrum (IR), field emission scanning electron microscopy (FESEM) and thermogravimetric analysis showed that a large number of PSS modification was on CNTs. The chemical state of CNTs, PSS and CNT/PSS was characterized by X photoelectron spectroscopy (XPS). It is found that the aromatic side of the PSS and the conjugated system on the surface of the CNTs are combined together by the effect of pi - pi; at the same time, the strong electron absorption substituent on the PSS benzene ring can use this pi - pi effect to absorb electrons from the CNTs and increase the electron cloud density of the sulfonyl group. Accordingly, we have first proposed that CNTs and polymer may be subjected to "pi - pi electron donor". The mechanism of non covalent modification, not simple Pi Pi action, was combined. (2) the adsorption mechanism of dye molecules was enhanced by CNT/PSS, and the adsorption mechanism was studied. The adsorption isotherm and adsorption kinetics were studied with methylene blue (MB), and the adsorption behavior of CNTs and CNT/PSS was studied by adsorption isotherm and adsorption kinetics. Compared with CNTs, the adsorption rate and adsorption capacity of MB were greatly improved, in which the adsorption capacity was 2 times more than that of the original, and the adsorption capacity reached 100 mg/g. And under the experimental conditions, CNT/PSS was used as an adsorbent only 3 min to close the adsorption equilibrium (CNTs need 10 min). In order to study the mechanism of adsorption enhancement, the adsorption interaction was used. Firstly, the adsorption site (active functional group) was accurately located, and it was found that MB was attracted by the sulfonic acid based electrostatic force on the surface of CNT/PSS by the two methylamine at one end by the adsorption of the pion - pi action of the aromatic ring and the wall of the CNTs tube, and then calculated the relative contribution of the electrostatic and PI - pi action to the adsorption capacity of 2:1. The advantages of electrostatic adsorption were explained reasonably from the angle of molecular configuration. Finally, the theoretical calculation proved that.2. six valence iron Fe (VI) was used as oxidant for CNTs and the non destructive covalent functionalization of CNTs, the first use of potassium ferrate K2Fe VI O4 as an oxidant for CNTs, and found that when concentrated sulfuric acid was the reaction medium, Fe was found. (VI) the rapid (3H) carboxylation of CNTs can be realized at a mild reaction condition (60 degrees C). The effect of oxidation is characterized by the colloid dispersion and the qualitative characterization of IR. This new oxidation method has the advantages of mild reaction conditions, high efficiency, no pollutants (the only by-product is Fe3+), and more importantly, the oxidation method will not destroy the conjugation of CNTs. Structure. The defect degree of CNTs before and after oxidation was measured by Raman spectrum. It was found that the oxidation of Fe (VI) did not introduce a new defect on the surface of CNTs. We analyzed the oxidation mechanism by combining the Raman spectrum, FESEM and XPS data. The results showed that the selectivity of Fe (VI) on the CNTs oxidation reaction occurred on the original sp3-C, not the C=C bond.CN. The sp3-C on the outer surface of the Ts is completely oxidized within 3 h, at the time the reaction ends and the reaction is extended to 6 h and does not increase the degree of reaction. As the non destructive oxidation both introduces oxygen containing functional groups and does not destroy the structure of CNTs, the yield of the oxidized CNTs exceeds the current highly effective but destructive mixed acid (HNO3/H2SO4) oxygen prevailing in 100wt%. with the current 100wt%.. The results are compared with the results of Fe (VI) oxidation, which further illustrates the specific / nondestructive oxidation mechanism of Fe (VI) to CNTs. This nondestructive oxidation lays the foundation for the non destructive covalent functionalization of CNTs.
【學位授予單位】：華東師范大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ127.11;TB383.1

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本文編號：1907707