本文關(guān)鍵詞： 碳納米管 分子力學(xué) 徑向穩(wěn)定性 坍塌 活化能　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：碳納米管作為一種新型的納米材料,具有很好的力學(xué)、電學(xué)、化學(xué)等性能,在許多領(lǐng)域有著廣泛的應(yīng)用前景,自發(fā)現(xiàn)以來受到人們越來越廣泛的關(guān)注。尤其是碳納米管具有中空的結(jié)構(gòu)和光滑的表面,其可作為藥物、流體及低維納米材料等的一種理想的傳輸通道和儲(chǔ)存裝置。然而碳納米管的傳輸效力和存儲(chǔ)能力與其結(jié)構(gòu)穩(wěn)定性密切相關(guān),因此開展具有不同手性和尺寸的碳納米管的穩(wěn)定性相關(guān)實(shí)驗(yàn)、理論及數(shù)值模擬研究具有重要的科學(xué)意義和實(shí)用價(jià)值。本文從分子力學(xué)模擬角度出發(fā),研究了常規(guī)和非常規(guī)碳納米管的結(jié)構(gòu)徑向穩(wěn)定性及構(gòu)型轉(zhuǎn)換,分析了手性、半徑及壁數(shù)對徑向穩(wěn)定性的影響,獲得了構(gòu)型轉(zhuǎn)換活化能與碳納米管半徑之間的關(guān)系,主要工作包括：常規(guī)單壁、雙壁及三壁碳納米管的徑向穩(wěn)定性及構(gòu)型轉(zhuǎn)換研究。基于分子力學(xué)模擬獲得了常規(guī)碳納米管徑向未坍塌及坍塌穩(wěn)定構(gòu)型,基于NEB方法分析了單壁、雙壁及三壁碳納米管從未坍塌到坍塌構(gòu)型轉(zhuǎn)換的最低能量路徑及活化能,進(jìn)一步分析了結(jié)構(gòu)徑向坍塌與碳管的手性和半徑之間的關(guān)系。研究結(jié)果表明：1)碳納米管向坍塌構(gòu)型轉(zhuǎn)換所需的活化能隨碳管半徑的增大而減小,半徑較大的碳納米管更易坍塌；2)鋸齒型碳納米管向坍塌構(gòu)型轉(zhuǎn)換所需的活化能略低于扶手椅型碳納米管向坍塌構(gòu)型轉(zhuǎn)換所需的活化能；3)內(nèi)管半徑相近且與單壁碳納米管半徑相當(dāng)時(shí),碳納米管坍塌活化能隨著壁數(shù)的增加而增加。非常規(guī)雙壁及三壁碳納米管的徑向穩(wěn)定性及構(gòu)型轉(zhuǎn)換研究�；谝延形墨I(xiàn)結(jié)果,構(gòu)造了非常規(guī)雙壁及三壁碳納米管未坍塌構(gòu)型,通過分子力學(xué)模擬獲得了非常規(guī)碳納米管的徑向坍塌穩(wěn)定構(gòu)型,并結(jié)合NEB方法獲得了構(gòu)型轉(zhuǎn)換的最低能量路徑與活化能,分析了非常規(guī)碳納米管徑向坍塌與管手性及半徑之間的關(guān)系。研究結(jié)果表明：1)當(dāng)內(nèi)管半徑較小時(shí),內(nèi)管不易發(fā)生坍塌且主要以缺陷的形式存在,其將導(dǎo)致非常規(guī)碳納米管向坍塌構(gòu)型轉(zhuǎn)換所需的活化能隨內(nèi)管半徑的增加而減�。�2)隨著內(nèi)管半徑的增大,內(nèi)管主要起支撐的作用,因此非常規(guī)碳納米管向坍塌構(gòu)型轉(zhuǎn)換所需的活化能隨內(nèi)管半徑的增大而增加。本文研究工作為進(jìn)一步理解碳納米管的徑向穩(wěn)定性提供了理論依據(jù),也為碳納米管在傳輸通道和儲(chǔ)存裝置中的應(yīng)用及其結(jié)構(gòu)穩(wěn)定性提供了理論指導(dǎo)。
[Abstract]:Carbon nanotubes (CNTs), as a new type of nanomaterials, have good mechanical, electrical and chemical properties, and have a wide range of applications in many fields. Carbon nanotubes, in particular, have hollow structures and smooth surfaces, which can be used as drugs. An ideal transport channel and storage device for fluid and low-dimensional nanomaterials, however, the transport efficiency and storage capacity of carbon nanotubes are closely related to their structural stability. Therefore, it is of great scientific significance and practical value to study the stability of carbon nanotubes with different chiral properties and sizes in theory and numerical simulation. The structure radial stability and configuration conversion of conventional and unconventional carbon nanotubes are studied. The effects of chirality, radius and wall number on radial stability are analyzed. The relationship between the configuration conversion activation energy and the radius of carbon nanotubes is obtained. The main work includes: the radial stability and configuration transformation of conventional single-walled, double-walled and three-walled carbon nanotubes. Based on molecular mechanics simulation, the radial uncollapsed and collapsing stable configurations of conventional carbon nanotubes are obtained, and the single wall is analyzed based on NEB method. The lowest energy path and activation energy of the two-wall and three-walled carbon nanotubes that never collapse into the collapse configuration transition, The relationship between the radial collapse of the structure and the chirality and radius of the carbon tube is further analyzed. The results show that the activation energy required for the transition of the carbon nanotube to the collapse configuration decreases with the increase of the radius of the carbon tube. Carbon nanotubes with larger radius are more likely to collapse.) the activation energy required for the conversion of sawtooth carbon nanotubes to collapse configurations is slightly lower than the activation energy required for the transition from armchair carbon nanotubes to collapse configurations. The inner tube radius is similar to that of single-walled carbon tubes. When the radius of nanotubes is equal, The activation energy of collapse of carbon nanotubes increases with the increase of the number of walls. The radial stability and configuration transformation of unconventional double-walled and three-walled carbon nanotubes are studied. Based on the results of previous literatures, the uncollapsed configurations of unconventional double-walled and three-walled carbon nanotubes are constructed. The radial collapse stable configuration of unconventional carbon nanotubes was obtained by molecular mechanics simulation, and the lowest energy path and activation energy of configuration conversion were obtained by NEB method. The relationship between the radial collapse of unconventional carbon nanotubes and the chirality and radius of the tubes is analyzed. The results show that when the radius of the inner tubes is small, the inner tubes are not easy to collapse and mainly exist in the form of defects. The activation energy required for the transition of the unconventional carbon nanotubes to the collapse configuration decreases with the increase of the inner tube radius.) with the increase of the inner tube radius, the inner tube plays a supporting role. Therefore, the activation energy required for the transition from unconventional carbon nanotubes to collapsing configurations increases with the increase of the radius of the inner tubes. This work provides a theoretical basis for further understanding the radial stability of carbon nanotubes. It also provides theoretical guidance for the application and structural stability of carbon nanotubes in transport channels and storage devices.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1;O613.71

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相關(guān)期刊論文 前1條

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本文編號(hào)：1497401