分子动力学模拟研究:低聚物在高分子母体中的扩散

Molecular Dynamics Simulation Studies: Diffusion of Oligomers in High Molecular Weight Matrix

采用显式表示氢原子的全原子模型,应用分子动力学模拟,在SGI O2 工作站和SGI Origin200服务器上用Molecular Simulations Inc. (MSI)的Cerius2软件研究甲基丙烯酸甲酯低聚物(聚合度n=1～10)在聚甲基丙烯酸甲酯母体中的扩散现象。结果表明,随着低聚物聚合度的增加,从单聚体到三聚体其扩散系数迅速减小,而从四聚体到十聚体其扩散系数几乎保持不变。而且,通过对模拟获得的扩散系数进行标度,所得结果能够与实验得到的数值符合得很好。对低聚物在高分子母体中的扩散机理进行了探讨,在聚合度很小时(三个以下),低聚物可能以整体迁移扩散为主,而在聚合度稍大时,则以局部蠕动扩散为主。

Molecular dynamics calculations were performed to simulate the diffusion of oligomers (from monomer to decamer) of methyl methacrylate (MMA) in high molecular weight poly(MMA) matrix on the Origin 200 on SGI. The calculated diffusion coefficient constants were in the same trend as the experimental data with the degree of polymerization increases. It was found that the diffusion coefficients of oligomers decrease rapidly from monomer to trimer and then keep nearly constant from tetramer to decamer as the degree of polymerization increases.