支撑聚合物薄膜界面和内部区域的集体运动及其与弛豫的关系。
Collective Motion in the Interfacial and Interior Regions of Supported Polymer Films and Its Relation to Relaxation.
作者信息
Zhang Wengang, Starr Francis W, Douglas Jack F
机构信息
Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.
Department of Physics , Wesleyan University , Middletown , Connecticut 06459-0155 , United States.
出版信息
J Phys Chem B. 2019 Jul 11;123(27):5935-5941. doi: 10.1021/acs.jpcb.9b04155. Epub 2019 Jun 27.
To understand the role of collective motion in the often large changes in interfacial molecular mobility observed in polymer films, we investigate the extent of collective motion in the interfacial regions of a thin supported polymer film and within the film interior by molecular dynamics simulation. Contrary to commonly stated expectations, we find that the extent of collective motion, as quantified by string-like molecular exchange motion, is similar in magnitude in the polymer-air interfacial layer as the film interior and distinct from the bulk material. This finding is consistent with Adam-Gibbs description of the segmental dynamics within mesoscopic film regions, where the extent of collective motion is related to the configurational entropy of the film as a rather than a locally defined extent of collective motion or configurational entropy.
为了理解集体运动在聚合物薄膜中观察到的界面分子迁移率的通常较大变化中的作用，我们通过分子动力学模拟研究了薄支撑聚合物薄膜界面区域和薄膜内部集体运动的程度。与通常的预期相反，我们发现，以线状分子交换运动量化的集体运动程度，在聚合物-空气界面层中的大小与薄膜内部相似，且与块状材料不同。这一发现与介观薄膜区域内链段动力学的亚当-吉布斯描述一致，其中集体运动程度与薄膜的构型熵相关，而不是与局部定义的集体运动程度或构型熵相关。
Zotero 插件