本文選題：TAADS + 分子動(dòng)力學(xué)�。� 參考：《山東大學(xué)》2017年博士論文

【摘要】：季銨鹽型TAADS表面活性劑體系由于其特殊的性質(zhì),在工業(yè)和生活中具有重要的應(yīng)用。實(shí)驗(yàn)發(fā)現(xiàn)以TAA+為反離子的表面活性劑體系比傳統(tǒng)的無機(jī)離子為反離子的表面活性劑體系具有更好的溶解性,而且當(dāng)抗衡離子體積比較大時(shí)(如TBADS體系)會(huì)出現(xiàn)濁點(diǎn)現(xiàn)象。實(shí)驗(yàn)工作者提出多種TAADS體系微觀膠束結(jié)構(gòu),用來解釋這種實(shí)驗(yàn)現(xiàn)象,包括用TBADS膠束之間的橋連模型,解釋類似體系的濁點(diǎn)現(xiàn)象。實(shí)驗(yàn)也發(fā)現(xiàn)TAADS對泡沫的穩(wěn)定性同樣也有很大的影響,因此理解TAADS在氣液界面的微觀結(jié)構(gòu)同樣具有重要的意義。雖然實(shí)驗(yàn)上對上述實(shí)驗(yàn)現(xiàn)象給予了充分關(guān)注,但是微觀結(jié)構(gòu)模型仍然沒有統(tǒng)一結(jié)論。分子動(dòng)力學(xué)模擬作為實(shí)驗(yàn)上的一種有效輔助手段,可以在分子水平上對所研究體系進(jìn)行微觀結(jié)構(gòu)和動(dòng)力學(xué)性質(zhì)的研究,因此利用分子動(dòng)力學(xué)方法也是解決TAADS相關(guān)體系一系列實(shí)驗(yàn)問題的有利工具。本論文圍繞TAADS體系通過分子動(dòng)力學(xué)的方法主要展開了一系列如下的研究:(一)通過分子動(dòng)力學(xué)的方法對于TAADS體系的相關(guān)性質(zhì)進(jìn)行了系統(tǒng)的研究,首先是TAADS體相的聚集行為,主要包括膠束的大小、形狀,表面極性頭的分布,內(nèi)部尾鏈末端碳的分布,表面活性劑分子不同位置的水化數(shù),以及表面活性劑分子和抗衡離子的結(jié)合方式等方面。結(jié)果表明膠束的半徑大小存在TMADSTEADSSDSTPADSTBADS的順序。模擬也表明烷基尾鏈上的一些亞甲基和末端C位于膠束的極化層。極性頭和抗衡離子存在四種結(jié)合方式,其中兩個(gè)TAA+尾鏈插入到DS-形成的膠束表面而形成混合膠束,此種方式是最多的結(jié)合模式。根據(jù)上述模擬理論,我們提出了分子水平上相關(guān)體系的動(dòng)力學(xué)模型。模擬結(jié)論支持前人實(shí)驗(yàn)上提出的EPR/TRFQ模型,是對實(shí)驗(yàn)上所提模型的進(jìn)一步驗(yàn)證和細(xì)化完善。分子動(dòng)力學(xué)模擬研究了 TAADS在氣液界面上的結(jié)構(gòu)特征,主要包括表面吸附膜的不同原子Z方向的概率分布、極性頭和抗衡離子的結(jié)合方式、吸附層第一水化層的吸附特征、尾鏈有序參數(shù)、以及弱氫鍵等。研究表明TAA+抗衡離子對表面活性劑極性頭的第一水化層有很大的影響,主要在于使得第一水化層的水分子數(shù)目變小。同時(shí),TAA+抗衡離子和極性頭之間形成了弱氫鍵,這些弱氫鍵限制水分子的運(yùn)動(dòng)。通過模擬發(fā)現(xiàn)極性頭和抗衡離子通過四種結(jié)合方式形成混合吸附層,其中第二種結(jié)合方式(抗衡離子TAA+兩個(gè)尾鏈插入到DS-形成的單層吸附表面從而形成混合吸附層)占據(jù)主導(dǎo)。利用分子動(dòng)力學(xué)模擬,得到了 TAADS的氣液界面上的吸附層的微觀結(jié)構(gòu)特征。最后通過模擬對TBADS和TBAC體系的異同進(jìn)行了詳細(xì)的研究,主要包括二者在不同溫度下的解離度、極性頭和抗衡離子之間的結(jié)合方式、抗衡離子的吸附自由能、以及膠束之間的動(dòng)力學(xué)行為和相互作用等。研究發(fā)現(xiàn)TBAC體系中TBA+離子的解離度高于TBADS體系的,但是溫度對解離度的影響是很小的。模擬表明極性頭的構(gòu)型和電荷的差異能夠影響TBA+離子和膠束間的結(jié)合方式。本文同時(shí)研究了 TBADS膠束之間的橋連模型并從微觀水平上得到了其具體的結(jié)構(gòu)。研究結(jié)果表明兩層TBA+抗衡離子橋連的DS-膠束構(gòu)型是最穩(wěn)定的。(二)用QH方法重點(diǎn)研究了 SDS膠束化過程中表面活性劑構(gòu)型熵的變化,其中包括平動(dòng)熵、轉(zhuǎn)動(dòng)熵和振動(dòng)熵的變化以及它們所占的比例。依據(jù)計(jì)算結(jié)果對膠束化過程中熵的來源給予了具體的解釋。研究結(jié)果表明膠束化過程中表面活性劑分子平動(dòng)熵的變化是很小的,這一點(diǎn)可以很好的解釋實(shí)驗(yàn)上發(fā)現(xiàn)的膠束和周圍環(huán)境的表面活性劑分子的交換現(xiàn)象。同時(shí)發(fā)現(xiàn)膠束化過程中熵的增加來自于水分子熵的增加和表面活性劑分子構(gòu)型熵的減小兩部分,其中水分子熵的增加占主導(dǎo)。最后重點(diǎn)介紹了 HSMD方法的基本原理和程序的編寫,以實(shí)現(xiàn)HSMD方法求熵�；诘玫降能壽E以及程序的改進(jìn),計(jì)算了 SDS膠束化熵的結(jié)果,與QH計(jì)算的結(jié)果作對比。HSMD方法的研究為將來研究復(fù)雜體系和探索新方法打下了基礎(chǔ)。
[Abstract]:The quaternary ammonium salt TAADS surfactant system has an important application in industry and life because of its special properties. It has been found that the surfactant system with TAA+ as the reverse ion has better solubility than the traditional inorganic ion surface active agent system, and when the counterion volume is relatively large (such as the TBADS body) A variety of TAADS system micro micelle structures are proposed to explain this experimental phenomenon, including the model of bridging between TBADS micelles to explain the cloud point phenomenon of the similar system. The experiment also found that TAADS also has a great influence on the stability of the foam. Therefore, it is understood that the TAADS is in the gas liquid interface. The observation structure is also of great significance. Although the experiment has given full attention to the experimental phenomena, the microstructure model still has no unified conclusion. As an effective auxiliary means of the experiment, the molecular dynamics simulation can study the microstructure and dynamics properties of the system at the molecular level. The use of molecular dynamics is also a useful tool for solving a series of experimental problems in TAADS related systems. In this paper, a series of studies have been carried out around the TAADS system through molecular dynamics methods: (1) a systematic study of the related properties of the TAADS system through molecular dynamics, first of all, TAADS The aggregation behavior of the body phase mainly includes the size, shape, distribution of the surface polar head, the distribution of carbon at the end of the internal tail chain, the number of hydration of the surfactant molecules in different positions, and the binding mode of the surfactant molecules and the counterions. The radius of the surface of the gelatin bundle exists in the order of TMADSTEADSSDSTPADSTBADS. The simulation also shows that some methylene and terminal C on the alkyl tail chain are located in the polarization layer of the micelle. There are four binding modes of polar head and counterion, of which two TAA+ tail chains are inserted into the micellar surface formed by DS- and form mixed micelles. This method is the most binding mode. According to the above simulation theory, we have proposed molecular level. The simulation results support the EPR/TRFQ model proposed by predecessors and further verify and refine the experimental model. The molecular dynamics simulation studies the structural characteristics of TAADS on the gas liquid interface, mainly including the probability distribution of the different atomic Z directions of the surface adsorption membrane, the polar head and the polar head. The binding mode of the ions, the adsorption characteristics of the first hydration layer of the adsorption layer, the order parameter of the tail chain, and the weak hydrogen bond. The study shows that the TAA+ counterions have a great influence on the first hydration layer of the surface active agent, mainly because the number of water molecules in the first hydration layer becomes smaller. At the same time, the TAA+ counterbalance ion and the polar head. The weak hydrogen bonds are formed. These weak hydrogen bonds restrict the movement of water molecules. Through the simulation, the polar head and counterions are found to form a mixed adsorption layer through four binding modes, of which second kinds of binding methods (the two tail chains of the anti ion TAA+ are inserted into the monolayer adsorbed surface formed by DS- to form a mixed adsorption layer) dominate. The microstructural characteristics of the adsorption layer on the gas-liquid interface of TAADS are obtained by mechanical simulation. Finally, the differences and similarities between the TBADS and TBAC systems are studied in detail, including the dissociation degree of the two at different temperatures, the binding mode between the polar head and the counterions, the adsorption free energy of the counterions, and the micelles. It is found that the dissociation degree of TBA+ ions in the TBAC system is higher than that of the TBADS system, but the effect of temperature on the degree of dissociation is very small. The simulation shows that the difference in the configuration and charge of the polar head can affect the binding mode between the TBA+ ions and the micelles. The bridge connection between the TBADS micelles is also studied in this paper. The model has obtained its specific structure at the micro level. The results show that the DS- micelle configuration of the two layer TBA+ counterbalance ion bridge is the most stable. (two) the changes in the configuration entropy of the surface active agent in the SDS micellization process are studied by QH method, including the change of the translational entropy, the change entropy and the vibration entropy and the ratio of their ratio. A specific explanation is given to the source of entropy in micellization according to the calculation results. The results show that the change of the molecular translational entropy of the surface active agent in the micellization is very small, which can explain the exchange phenomenon of the surfactant molecules of the micelles and the surrounding environment. And the micellization is also found. The increase of entropy in the process comes from the increase of water molecular entropy and the decrease of two parts of the molecular configuration entropy of surface active agent, in which the increase of water molecular entropy is dominant. Finally, the basic principle of HSMD method and the programming of the program are introduced in order to realize the entropy of HSMD. Based on the track track and the improvement of the program, the SDS micellization is calculated. The result of entropy is compared with the result of QH calculation. The research of.HSMD method lays a foundation for future research of complex system and exploration of new methods.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：O647.2

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