我們利用分子動力學模擬聚甲基丙烯酸甲酯(PMMA)在奈米尺度下，藉由改變支鏈的排列(同位或異位)，來討論因支鏈不同排列而產生的不同構形對聚甲基丙烯酸甲酯影響。第一階段先以分子動力學模擬聚甲基丙烯酸甲酯之徑向分佈函數、玻璃轉化溫度，並且與文獻驗證。第二階段則進行一系列的高分子物性計算，討論不同構形對聚甲基丙烯酸甲酯的影響，以觀察其在奈米尺度下的運動行為。最後我們在討論不同密度、溫度、構形下，聚甲基丙烯酸甲酯在苯溶劑下的差異。
首先，我們將探討所模擬出來聚甲基丙烯酸甲酯的一些基本物理性質，如鍵長、鍵角、徑向分佈函數、玻璃轉化溫度…等等，並與文獻資料逐一比照，以提高模擬材料的準確性。待確認無誤後，對不同排列的聚甲基丙烯酸甲酯，計算其特徵值、熱膨脹係數、相對時間、表面活化能…等等，觀察比較由於構形的不同，在微觀下對聚甲基丙烯酸甲酯的影響，並和文獻比較。最後.再將其放入苯溶劑中，觀察其擴散係數，討論不同鏈長和溫度下聚甲基丙烯酸甲酯的擴散行為，希望藉由分子動力模擬在奈米尺度下的有效分析，能夠解決更多的工程問題。

In this research, molecular dynamics simulation is adopted to simulate the influence of different conformational of Poly(methylMeth acrylate). First, we simulate the glass transition temperature and radial distribution function with Poly(methylMeth acrylate) and compare with the literature. Then, we compute a series physical property of Poly(methylMeth acrylate) to see its behaviors in microsropc.
Besides, behaviors of fluids of Poly(methylMeth acrylate) such as bond-length、bond-angle、space-time correlation function、chararcteristic ratio、and apparent activation energy will be check with the literature. After checking the material, we will analysis Mean square displacement with sydiotatic and isotatic PolymethylMeth acrylate in benzene .Wish we can use the molecular dynamics simulation to solve more engineering problems.
Key Word：Molecular Dynamics Simulation、Radial Distribution Function、 PolymethylMeth acrylate、Mean square displacement

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