Capillary-driven indentation of a microparticle into a soft, oil-coated substrate
Capillary-driven indentation of a microparticle into a soft, oil-coated substrate
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DOI：
10.1039/d0sm00296h
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发表时间：
2020-07-07
期刊：
影响因子：
3.4
通讯作者：
Pham, Jonathan T.
中科院分区：
文献类型：
--
作者：
Glover, Justin D.;Pham, Jonathan T.
在许多情况下，从关节软骨上的滑液到潮湿环境中的粘合剂，柔软的液体涂层层与坚硬表面之间的小规模接触是很常见的。此外，许多软粘接接触的模型研究都是用软硅弹性体进行的，当模量较低时，软硅弹性体具有非交联的液体分子（即硅油）。我们研究了软基板上硅油层的厚度与与交联PDMS接触的玻璃微球的压痕深度的关系，其模量为o10 kPa。随着油层厚度的减小，颗粒更多地缩进基体。这是由于表面存在液体层，导致毛细力向下拉颗粒。提出了一个简单的模型，该模型将油层的毛细力和颗粒与基体的最小粘附力与基体的弹性力和表面张力相平衡，以预测颗粒压痕深度。
Small scale contact between a soft, liquid-coated layer and a stiff surface is common in many situations, from synovial fluid on articular cartilage to adhesives in humid environments. Moreover, many model studies on soft adhesive contacts are conducted with soft silicone elastomers, which possess uncrosslinked liquid molecules (i.e. silicone oil) when the modulus is low. We investigate how the thickness of a silicone oil layer on a soft substrate relates to the indentation depth of glass microspheres in contact with crosslinked PDMS, which have a modulus of o10 kPa. The particles indent into the underlying substrate more as a function of decreasing oil layer thickness. This is due to the presence of the liquid layer at the surface that causes capillary forces to pull down on the particle. A simple model that balances the capillary force of the oil layer and the minimal particle-substrate adhesion with the elastic and surface tension forces from the substrate is proposed to predict the particle indentation depth.