Pangule Ravindra C, Banerjee Indrani, Sharma Ashutosh
Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016, India.
J Chem Phys. 2008 Jun 21;128(23):234708. doi: 10.1063/1.2940330.
We show that the surface of a thin elastomer-metal (aluminum) hybrid bilayer becomes spontaneously patterned when brought in adhesive contact with a rigid surface. The self-organized surface patterns show three distinct morphological phases-columns, labyrinths, and holes-depending on the area of contact. The characteristic wavelength of these patterns is found to be 2.94+/-0.20 times the total film thickness, independent of the morphological phase and the surface properties of the contacting surface. Interestingly, the metal films 60-120 nm thick showed the same scaling, but the bilayers with thicker metal films were completely stable. This observation demonstrates for the first time a "hard" transition to the instability as the elastic stiffness of the film is varied. We also report a protocol for alignment of the instability patterns and for transferring the metal patterns to another surface.
我们发现，当薄弹性体-金属（铝）混合双层与刚性表面进行粘性接触时，其表面会自发形成图案。自组织表面图案呈现出三种不同的形态相——柱状、迷宫状和孔洞状，这取决于接触面积。这些图案的特征波长为总膜厚的2.94±0.20倍，与形态相以及接触表面的性质无关。有趣的是，60 - 120纳米厚的金属膜呈现出相同的比例关系，但金属膜更厚的双层则完全稳定。这一观察首次证明了随着膜的弹性刚度变化，会发生向不稳定性的“硬”转变。我们还报告了一种使不稳定性图案对齐并将金属图案转移到另一个表面的方法。
