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標題: | 分散劑於α–氧化鋁表面之吸附研究 Adsorption Phenomena of Polyelectrolyte Dispersants on α-Alumina Surfaces |
作者: | Hsin-Yi Chen 陳馨怡 |
指導教授: | 韋文誠(Wen-Cheng Wei),陳俊杉(Chuin-Shan Chen) |
關鍵字: | 分子動力學模擬,原子力顯微鏡 (AFM),α-Al2O3,分散劑,吸附,PAA,PMA,PMMA,PE,PAMC, Alumina,Dispersant,adsorption,Molecular dynamics (MD) simulation,Atomic force microscopy (AFM),PAA,PMA,PMMA,PE,PAMC, |
出版年 : | 2005 |
學位: | 碩士 |
摘要: | 本研究之目的即在了解分散劑擴散至粉體表面之吸附型態,進而計算表面間之立體阻隔作用力存在與否,從而推論出此系統是否達到穩定分散。為觀察分散劑(高分子或聚電解質),本研究用分子動力學模擬 ( Molecular Dynamics/MD Simulation ) 觀察分散劑於α-Al2O3表面之立體阻隔作用 ( steric force ) ,並以原子力顯微鏡 ( AFM ) 及理論與模擬結果做比較。藉由控制不同pH值,讓分散劑,丙烯酸 (PAA) ,以直立型式 (tail) 吸附在α-氧化鋁表面上,並以吸附量實驗所推測出來的吸附型態和模擬作比對。進而以此模型為基礎,建構二個表面之系統,並在間距為一及二倍PAA鏈長範圍,計算其作用力。最後,再以原子力顯微鏡所測出的立體阻隔作用力(steric force)和模擬作比較。在分散劑鏈長為1.6nm及表面距離間距為1.6 ~ 3.2nm時,由模擬、實驗及理論可看出有立體阻隔作用力存在,可推論此分散劑可提供良好之分散效果。本研究係採用二種不同解離度之PAA吸附在 (001) α-Al2O3表面,利用分子動力學模擬,原子力顯微鏡及立體阻隔理論觀察表面間之作用力。結果發現︰使用鏈長為 1.6nm完全解離之PAA,因其分子間有很強的排斥力而使之以直立型式吸附在表面上,從而提供一穩定之立體阻隔排斥力於粉體表面間,且此確實於分子動力學模擬中可觀察到,由AFM及理論可得與模擬一致性之結果。 This study presents a simulation procedure and demonstrates the simulation results in comparison with the adsorption of polymers by atomic force microscopy (AFM) experiment. The adsorption process of dispersants interplay with α-Al2O3 surfaces, adsorbed conformations, and the steric potential interaction are of interest. The procedure employed molecular dynamics (MD) techniques to execute simulations on the interactions of polyacrylic acid (PAA), polymethacrylic acid (PMA), polymethyl methacrylate (PMMA), polyethylene (PE), and Poly 2-Acrylamido-2-methylpropane sulfonic acid-co-Methacrylic acid-co-(β-carboxylate (hydroxyl acrylic polyethylester))) (PAMC) polymers with various dissociated fraction, 0.1、0.5、1, with O- or Al-terminated on , , , , and planes of Al2O3 surfaces, which were constructed in nano-scale thickness (ca. 1~1.3 nm). Ten parameters, i.e., optimal thickness, Al2O3 planes, termination, functional groups, molecular weight, dissociated fraction, chain numbers, medium, and the pH effects on steric force between two surfaces has been studied. Direct measurements of the interaction forces between Al2O3 surfaces by AFM in the absence and presence of low-molecular-weight (MW = 5000) poly (acrylic acid) (PAA) were conducted at different pH solutions. The measurement at high pH where the adsorbed, highly charged anionic polyelectrolyte extends into the solution, leads to a combination of steric and electrostatic interactions. The buildup of PAA at the interface is closely related to manifest attractive bridging interactions, adhesion, during approaching route. The force results are compared the MD simulation by the same dispersant. In the next section, comparing different polyelectrolytes to observe the factor to dispersion is proceeding. Eventually, our destination is to predict the better dispersants by simulation in lieu of synthesis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/35653 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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