Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California 95616, USA.
Phys Chem Chem Phys. 2009 Dec 21;11(47):11324-32. doi: 10.1039/b911311h. Epub 2009 Oct 21.
The properties of polystyrene brushes in dry conditions and in toluene solution are studied as a function of grafting density using molecular dynamics simulations. Both, individual brushes and double layers of opposing brushes are considered, the structural properties of which were found to be similar. The density profiles show very pronounced density oscillations which extend up to approximately 1.8 nm and fall into two groups of three peaks each. These features are observed regardless of grafting density and solvent conditions. In the absence of solvent, the chains undergo a transition from an oblate to a spherical shape as the grafting density increases. In contrast, in good solvent, the chains remain spherical independent of the grafting density. Solvation also increases the extension of the polystyrene chains roughly by a factor 2.5. Isotropic and two-dimensional radial distribution functions are used to characterize the structure of the polystyrene brushes. Toluene is observed to form up to four layers at the base of the grafted chains irrespective of grafting density.
使用分子动力学模拟研究了聚苯乙烯刷在干燥条件和甲苯溶液中的性能，作为接枝密度的函数。考虑了单个刷和相反刷的双层，发现它们的结构性质相似。密度分布显示出非常明显的密度振荡，延伸至约 1.8nm，并分为两组，每组三个峰。无论接枝密度和溶剂条件如何，都可以观察到这些特征。在没有溶剂的情况下，随着接枝密度的增加，链从扁长形转变为球形。相比之下，在良溶剂中，链的形状保持球形，与接枝密度无关。溶剂化作用还使聚苯乙烯链的延伸度增加了约 2.5 倍。各向同性和二维径向分布函数用于表征聚苯乙烯刷的结构。无论接枝密度如何，甲苯在接枝链的底部都可以形成多达四层。
