Pattern-directed dewetting of ultrathin polymer films
Pattern-directed dewetting of ultrathin polymer films
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DOI：
10.1021/la020180l
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发表时间：
2002-09-03
期刊：
影响因子：
3.9
通讯作者：
Karim, A
中科院分区：
文献类型：
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作者：
Sehgal, A;Ferreiro, V;Karim, A
我们利用化学图案化的基板阵列逐渐变窄的条纹（1-15微米），以研究图案尺寸的形态上的润湿聚苯乙烯薄膜的影响。的反润湿图案的旋节状的高度波动的规模和取向耦合到所施加的基板化学频率，提供了一个强大的手段形态控制。去湿图案与导致液滴阵列形成的基板图案周期相关。测量结果证实了最近的数值模拟的存在的上，下截止尺度的去湿流体的模式识别的Kampta和夏尔马。对于小于非图案化基底上的特征尺度的图案尺寸，液滴变得各向异性，因为它们粗化到与条纹宽度相当的尺度，然后经历形态学过渡到跨越多个条纹的圆形液滴。如理论所示，这导致液滴尺寸和接触角的量化。
We utilize chemically patterned substrates with arrays of progressively narrower stripes (1-15 mum) to investigate the influence of pattern size on the morphology of ultrathin dewetting polystyrene films. The scale and orientation of the spinodal-like height fluctuations of the dewetting patterns are coupled to the imposed substrate chemical frequency, providing a powerful means of morphological control. Dewetting patterns are correlated to the substrate pattern period leading to the formation of droplet arrays. The measurements confirm recent numerical simulations by Kargupta and Sharma of the existence of upper and lower cutoff scales for pattern recognition of a dewetting fluid. For pattern dimensions less than the characteristic scale on nonpatterned substrates, the droplets become anisotropic as they coarsen to a scale comparable to the stripe width, and then undergo a morphological transition to circular droplets that cross multiple stripes. This leads to quantization of droplet size and contact angles, as indicated by, theory.