Kyrylyuk Andriy V, Fraaije Johannes G E M Hans
Theoretical and Polymer Physics Group, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
J Chem Phys. 2006 Oct 28;125(16):164716. doi: 10.1063/1.2360947.
The dynamics of alignment of microstructure in confined films of diblock copolymer melts in the presence of an external electric field was studied numerically. We consider in detail a symmetric diblock copolymer melt, exhibiting a lamellar morphology. The method used is a dynamic mean-field density functional method, derived from the generalized time-dependent Ginzburg-Landau theory. The time evolution of concentration variables and therefore the alignment kinetics of the morphologies are described by a set of stochastic equations of a diffusion form with Gaussian noise. We investigated the effect of an electric field on block copolymers under the assumption that the long-range dipolar interaction induced by the fluctuations of composition pattern is a dominant mechanism of electric-field-induced domain alignment. The interactions with bounding electrode surfaces were taken into account as short-range interactions resulting in an additional term in the free energy of the sample. This term contributes only in the vicinity of the surfaces. The surfaces and the electric field compete with each other and align the microstructure in perpendicular directions. Depending on the ratio between electric field and interfacial interactions, parallel or perpendicular lamellar orientations were observed. The time scale of the electric-field-induced alignment is much larger than the time scale of the surface-induced alignment and microphase separation.
对在外部电场存在下双嵌段共聚物熔体受限薄膜中微观结构的排列动力学进行了数值研究。我们详细考虑了一种呈现层状形态的对称双嵌段共聚物熔体。所采用的方法是一种动态平均场密度泛函方法，它源自广义的含时金兹堡 - 朗道理论。浓度变量的时间演化以及形态的排列动力学由一组具有高斯噪声的扩散形式的随机方程描述。我们在组成图案波动引起的长程偶极相互作用是电场诱导畴排列的主导机制这一假设下，研究了电场对嵌段共聚物的影响。与边界电极表面的相互作用被视为短程相互作用，这导致样品自由能中出现一个附加项。该项仅在表面附近起作用。表面和电场相互竞争，并使微观结构在垂直方向上排列。根据电场与界面相互作用之间的比例，观察到了平行或垂直的层状取向。电场诱导排列的时间尺度远大于表面诱导排列和微相分离的时间尺度。
