Department of Physics, Williams College, Williamstown, MA, USA.
Soft Matter. 2019 Feb 6;15(6):1327-1334. doi: 10.1039/c8sm02075b.
We characterize the mechanical recovery of compliant silicone gels following adhesive contact failure. We establish broad, stable adhesive contacts between rigid microspheres and soft gels, then stretch the gels to large deformations by pulling quasi-statically on the contact. Eventually, the adhesive contact begins to fail, and ultimately slides to a final contact point on the bottom of the sphere. Immediately after detachment, the gel recoils quickly with a self-similar surface profile that evolves as a power law in time, suggesting that the adhesive detachment point is singular. The singular dynamics we observe are consistent with a relaxation process driven by surface stress and slowed by viscous flow through the porous, elastic network of the gel. Our results emphasize the importance of accounting for both the liquid and solid phases of gels in understanding their mechanics, especially under extreme deformation.
我们描述了柔软的硅酮凝胶在黏附接触失效后的力学恢复过程。我们在刚性微球和软凝胶之间建立了广泛而稳定的黏附接触，然后通过对接触处的准静态拉伸使凝胶产生大变形。最终，黏附接触开始失效，并最终滑动到球体底部的最终接触点。在脱离接触后，凝胶会迅速回弹，其表面轮廓呈自相似形式，且随时间呈幂律演化，表明黏附脱离点是奇异的。我们观察到的奇异动力学与由表面应力驱动、并通过凝胶多孔弹性网络的黏性流减缓的松弛过程相一致。我们的研究结果强调了在理解凝胶力学行为时，特别是在极端变形条件下，考虑凝胶的液体和固体相的重要性。
