Dewetting of thin films on periodic physically and chemically patterned surfaces
Dewetting of thin films on periodic physically and chemically patterned surfaces
复制标题
DOI：
10.1021/la010469n
复制
发表时间：
2002-03-05
期刊：
影响因子：
3.9
通讯作者：
Sharma, A
中科院分区：
文献类型：
--
作者：
Kargupta, K;Sharma, A
在三维非线性模拟的基础上，研究了物理和化学非均质图案化表面上液体薄膜中图形的不稳定性、动力学和形态转变。在化学条纹表面(由交替的更少和更多的可湿条纹组成)，当它们的间距低于不稳定的特征长度标度(波长(H))时，膜破裂在一些潜在不稳定的非可湿条纹上被抑制，该特征长度标度与较少润湿条纹上的不稳定的调幅长度标度(波长(L))处于同一量级。仅当(A)衬底图案的周期位于波长(H)和波长(H)之间，以及(B)较不湿的条纹宽度在由较低的临界长度和较高的过渡长度所限定的范围内时，薄膜图案才紧密地复制衬底表面能量图案，在较低的临界长度以下不会发生非均匀破裂，在较高的过渡长度之上形成与衬底图案几乎不相似的复杂的形态特征。周期性物理非均匀表面上的薄膜图案显示，当表面的周期小于在最小薄膜厚度下估计的调幅波长的约0.8倍时，理想模板的损失。在物理化学图案化的周期性表面上，化学非均质性在很大程度上控制了薄膜的图样，而小到中等的物理非均质性的影响很小。
The instability, dynamics, and morphological transitions of patterns in thin liquid films on physically and chemically heterogeneous patterned surfaces are investigated on the basis of 3D nonlinear simulations. On a chemically striped surface (consisting of alternating less and more wettable stripes) the film breakup is suppressed on some potentially destabilizing nonwettable stripes when their spacing is below a characteristic length scale of instability (lambda(h)), which is of the same order as the spinodal length scale (lambda(l)) of instability on the less wettable stripes. The thin film pattern replicates the substrate surface energy pattern closely only when (a) the periodicity of the substrate pattern lies between lambda(h) and 2lambda(h) and (b) the less wettable stripe width is within a range bounded by a lower critical length, below which no heterogeneous rupture occurs, and an upper transition length, above which complex morphological features bearing little resemblance to the substrate pattern are formed. The thin film pattern on a periodic physically heterogeneous surface shows the loss of ideal templating when the periodicity of the surface is smaller than about 0.8 times the spinodal wavelength evaluated at the minimum film thickness. On a physicochemically patterned periodic surface, the chemical heterogeneity largely controls the thin film pattern and the effect of small to moderate physical heterogeneity is minimal.