Miller Joia M, Hall Doug, Robaszewski Joanna, Sharma Prerna, Hagan Michael F, Grason Gregory M, Dogic Zvonimir
Department of Physics, Brandeis University, Waltham, MA 02454, USA.
Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
Sci Adv. 2020 Jul 29;6(31):eaba2331. doi: 10.1126/sciadv.aba2331. eCollection 2020 Jul.
Using theory and experiments, we study the interface between two immiscible domains in a colloidal membrane composed of rigid rods of different lengths. Geometric considerations of rigid rod packing imply that a domain of sufficiently short rods in a background membrane of long rods is more susceptible to twist than the inverse structure, a long-rod domain in a short-rod membrane. The midplane tilt at the interdomain edge forces splay, which, in turn, manifests as spontaneous edge curvature with energetics controlled by the length asymmetry of constituent rods. A thermodynamic model of such tilt-curvature coupling at interdomain edges explains a number of experimental observations, including annularly shaped long-rod domains, and a nonmonotonic dependence of edge twist on domain radius. Our work shows how coupling between orientational and compositional degrees of freedom in two-dimensional fluids gives rise to complex shapes of fluid domains, analogous to shape transitions in 3D fluid vesicles.
我们运用理论和实验方法，研究了由不同长度刚性棒组成的胶体膜中两个不混溶区域之间的界面。刚性棒堆积的几何考量表明，在长棒背景膜中存在足够短棒的区域比相反结构（短棒膜中的长棒区域）更容易发生扭曲。域间边缘处的中平面倾斜会引发展曲，进而表现为自发边缘曲率，其能量学由组成棒的长度不对称性控制。这种域间边缘处倾斜 - 曲率耦合的热力学模型解释了许多实验观测结果，包括环形长棒区域以及边缘扭曲对域半径的非单调依赖性。我们的工作展示了二维流体中取向和成分自由度之间的耦合如何产生流体域的复杂形状，这类似于三维流体囊泡中的形状转变。
