Linking energy loss in soft adhesion to surface roughness
Linking energy loss in soft adhesion to surface roughness
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DOI：
10.1073/pnas.1913126116
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发表时间：
2019-12-17
影响因子：
11.1
通讯作者：
Jacobs, Tevis D. B.
中科院分区：
文献类型：
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作者：
Dalvi, Siddhesh;Gujrati, Abhijeet;Jacobs, Tevis D. B.
在运输（轮胎，垫圈和密封件），生物材料，微接触印刷和软机器人领域，对软材料粘附的机械理解至关重要。长期以来，测量表明，接触的表观粘附功始终低于材料的固有粘附功，并且在分离期间存在粘附滞后，通常由粘弹性耗散解释。仍然缺乏的是一个定量的实验验证之间的联系，粘附和测量的地形。在这里，我们使用的接触尺寸的原位测量，以调查软弹性聚二甲基硅氧烷半球（模量范围从0.7至10 MPa）的粘附行为在4个不同的多晶金刚石衬底的地形特征跨越8个数量级，包括下降到埃尺度。结果表明，表观粘附功的减少等于实现共形接触所需的能量。此外，在接触和移除期间的能量损失等于粘附的本征功和真实接触面积的乘积。这些研究结果提供了一个简单的机制，定量链接广泛观察到的粘附滞后粗糙度，而不是粘弹性耗散。
A mechanistic understanding of adhesion in soft materials is critical in the fields of transportation (tires, gaskets, and seals), biomaterials, microcontact printing, and soft robotics. Measurements have long demonstrated that the apparent work of adhesion coming into contact is consistently lower than the intrinsic work of adhesion for the materials, and that there is adhesion hysteresis during separation, commonly explained by viscoelastic dissipation. Still lacking is a quantitative experimentally validated link between adhesion and measured topography. Here, we used in situ measurements of contact size to investigate the adhesion behavior of soft elastic polydimethylsiloxane hemispheres (modulus ranging from 0.7 to 10 MPa) on 4 different polycrystalline diamond substrates with topography characterized across 8 orders of magnitude, including down to the angstrom scale. The results show that the reduction in apparent work of adhesion is equal to the energy required to achieve conformal contact. Further, the energy loss during contact and removal is equal to the product of the intrinsic work of adhesion and the true contact area. These findings provide a simple mechanism to quantitatively link the widely observed adhesion hysteresis to roughness rather than viscoelastic dissipation.