A Molecular dynamics study of the mechanical property and Dynamic Behavior of PMMA (Polymethyl Methacrylate) thin membrane absorbed on Au substrate

• Main Authors: Ching-Ho Cheng, 鄭敬禾
• Other Authors: Shin-Pon Ju
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/fc449s

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 95 === Molecular dynamics simulations is performed to investigate the structural properties of the PMMA (poly(methyl methacrylate)) thin film on an Au (111) surface. According to model the MMA (methyl methacrylate) thin film on an Au (111) surface, we found that there is a significant effect on the density profile near the interface between the thin film and Au substrate. Moreover, the density clearly decreases in this region as the temperature increases. Next, we calculated and examined the relationships among the stress, surface tension, average potential energy, orientation, and formation energy. In order to investigate the material properties of MMA nano-thin films of different thicknesses on the Au (111) surface, the simulation for the nano-indentation process is used to obtain the material properties of MMA nano-thin films. And the deformation mechan- ism of the MMA thin films during the course of the indentation is also discussed in this study, completely. Furthermore, Molecular dynamics simulations were employed to investigate chain-length effect on conformations of methyl methacrylate (MMA)-oligomer thin films on an Au (111) substrate. For short chain films, there is a sharp peak in the density profile of the MMA monomers for the adsorption region and the thin films exhibit a flattened conformation in the adsorption and the surface regions. For long chain films, however, there is no sharp peak in the whole density profiles and a snake-like conformation appears in the adsorption region, which shrinks and convolutes gradually in the bulk region and even more in the surface region of the thin film.