Shao Xingchen, Wang Yumo, Frechette Joelle
Chemical and Biomolecular Engineering Department, University of California, Berkeley, California 94720, USA.
National Engineering Laboratory for Pipeline Safety, Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum, Beijing, 18# Fuxue Road, Changping District, 102249 Beijing, China.
J Chem Phys. 2023 Oct 7;159(13). doi: 10.1063/5.0167300.
We report on viscous adhesion measurements conducted in sphere-plane geometry between a rigid sphere and soft surfaces submerged in silicone oils. Increasing the surface compliance leads to a decrease in the adhesive strength due to elastohydrodynamic deformation of the soft surface during debonding. The force-displacement and fluid film thickness-time data are compared to an elastohydrodynamic model that incorporates the force measuring spring and finds good agreement between the model and data. We calculate the pressure distribution in the fluid and find that, in contrast to debonding from rigid surfaces, the pressure drop is non-monotonic and includes the presence of stagnation points within the fluid film when a soft surface is present. In addition, viscous adhesion in the presence of a soft surface leads to a debonding process that occurs via a peeling front (located at a stagnation point), even in the absence of solid-solid contact. As a result of mass conservation, the elastohydrodynamic deformation of the soft surface during detachment leads to surfaces that come closer as the surfaces are separated. During detachment, there is a region with fluid drainage between the centerpoint and the stagnation point, while there is fluid infusion further out. Understanding and harnessing the coupling between lubrication pressure, elasticity, and surface interactions provides material design strategies for applications such as adhesives, coatings, microsensors, and biomaterials.
我们报告了在刚性球体与浸没在硅油中的软表面之间的球-平面几何形状中进行的粘性粘附力测量。由于在脱粘过程中软表面的弹性流体动力变形，表面柔顺性的增加导致粘附强度降低。将力-位移和流体膜厚度-时间数据与包含测力弹簧的弹性流体动力学模型进行比较，发现该模型与数据之间具有良好的一致性。我们计算了流体中的压力分布，发现与从刚性表面脱粘不同，当存在软表面时，压力降是非单调的，并且在流体膜内存在驻点。此外，即使在没有固-固接触的情况下，软表面存在时的粘性粘附也会导致通过剥离前沿（位于驻点处）发生脱粘过程。由于质量守恒，分离过程中软表面的弹性流体动力变形导致表面在分离时靠得更近。在分离过程中，中心点和驻点之间存在流体排出区域，而在更远的地方存在流体注入。理解和利用润滑压力、弹性和表面相互作用之间的耦合为粘合剂、涂层、微传感器和生物材料等应用提供了材料设计策略。
