Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018, China.
State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
J Chem Phys. 2017 Sep 21;147(11):114903. doi: 10.1063/1.5004181.
The self-assembly behavior of AB diblock copolymers under cylindrical confinement is investigated using the self-consistent field theory. We focus on the impact of the confinement on the order-order transitions of three-dimensional morphologies by constructing two types of phase diagrams with continuously varying block compositions. One type is with respect to the block composition and the immiscibility parameter for various pore sizes, in which the order-order transitions are shown to be strongly impacted by the pore curvature and thus largely different from the bulk ones. Note that the morphologies are categorized by the intrinsical geometry of their domains, i.e., that helical morphologies are regarded as one type of cylindrical phase. Another type of phase diagram is with respect to the block composition and the pore diameter, which exhibits a number of interesting order-order transitions, especially the transition sequence from a straight line of spheres, to one straight cylinder and stacked disks as the pore diameter increases. A critical point is observed at which the stability region of the straight cylinder vanishes and thereby the spheres transform into the stacked disks continuously. The mechanism of these phase transitions is rationalized in the context of the bulk factors as well as an additional factor, i.e., the competition between the spontaneous curvature of the copolymer and the imposed curvature by the nanopore.
使用自洽场理论研究了 AB 两嵌段共聚物在圆柱受限条件下的自组装行为。我们通过构建两种具有连续变化嵌段组成的相图，重点研究了受限条件对三维形貌的有序-无序转变的影响。一种相图是关于不同孔径的嵌段组成和不相容参数，其中有序-无序转变强烈地受到孔曲率的影响，因此与体相有很大的不同。需要注意的是，形态是通过其域的内在几何结构来分类的，即螺旋形态被视为圆柱相的一种类型。另一种相图是关于嵌段组成和孔径的，它表现出许多有趣的有序-无序转变，特别是从直线球到单一圆柱和堆叠盘的转变序列，随着孔径的增加。在一个临界点处，直圆柱的稳定区域消失，因此球体会连续地转变为堆叠盘。这些相转变的机制在体相因素以及一个附加因素的背景下得到了合理化，即共聚物的自发曲率和纳米孔施加的曲率之间的竞争。
