Department of Chemical Engineering, Indian Institute of Technology, Kanpur-208016, U.P., India.
Langmuir. 2012 Oct 16;28(41):14784-91. doi: 10.1021/la302460y. Epub 2012 Oct 4.
Inspired by the natural adhesives in the toe pads of arthropods and some other animals, we explore the effectiveness and peel failure of a thin viscoelastic liquid film anchored on a micropatterned elastic surface. In particular, we focus on the role of the substrate pattern in adhesion energy of the liquid layer and in allowing its clean separation without cohesive failure. Peel tests on the microfabricated wet adhesives showed two distinct modes of adhesive (interfacial) and cohesive (liquid bulk) failures depending on the pattern dimensions. The adhesion energy of a viscoelastic liquid layer on an optimized micropatterned elastic substrate is ~3.5 times higher than that of a control flat bilayer and ~26 times higher than that of a viscoelastic film on a rigid substrate. Adhesive liquid layers anchored by narrow microchannels undergo clean, reversible adhesive failure rather than the cohesive failure seen on flat substrates. An increase in the channel width engenders cohesive failure in which droplets of the wet adhesive remain on the peeled surface.
受节肢动物和其他一些动物脚趾垫中的天然粘合剂的启发，我们探索了薄的粘弹性液膜在微图案化弹性表面上的固定效果和剥落失效。具体而言，我们专注于基底图案在液层粘附能以及在没有内聚失效的情况下实现其清洁分离方面的作用。对微加工湿粘合剂进行的剥离测试表明，根据图案尺寸，存在两种不同的粘合（界面）和内聚（液体整体）失效模式。在优化的微图案化弹性基底上，粘弹性液层的粘附能比对照的双层平板高约 3.5 倍，比刚性基底上的粘弹性膜高约 26 倍。由窄微通道固定的粘性液层经历干净、可重复的粘性失效，而不是在平板基底上看到的内聚失效。增加通道宽度会导致内聚失效，其中湿粘合剂的液滴会残留在剥落的表面上。
