Mechanics of Miniature Surface Craters for Reversible Adhesion

该奖项支持陨石坑表面力学的基础研究。可逆胶粘剂的设计目的是形成暂时的粘合，理想情况下可以重复使用，并且能够牢固粘合。这种可逆粘合剂可以广泛应用于垂直安装和攀爬，可释放的晶圆和芯片处理，以及可重复使用的生物集成电子产品。众所周知，可逆粘附可以通过表面相互作用，如范德华（vdW），毛细管力，静电力以及体积效应，如吸力来实现。壁虎微原纤维具有不同的尖端形状，包括凹形状，表面相互作用引起的粘附性已经得到了很好的研究。但在微观尺度上，吸力的作用被广泛忽视。然而，制造具有大长宽比的微纤维既昂贵又耗时。如果一组中尺度凹坑能够提供高粘接强度和可逆性，它们可能成为微纤维的实用替代品。本研究的结果将指导陨石坑表面的设计和优化，并在广泛的尺度上为吸力效应的争论提供明确的答案。它还将为开发用于工程和医学各种应用的新型优质粘合剂开辟一条途径。在以往教育和推广活动的良好记录的基础上，pi将继续通过新生REU为来自少数民族学院的本科生和高中生以及德克萨斯大学奥斯汀分校的工程项目（WEP）女性提供专门设计的研究机会。本研究的研究目的是验证这样一个假设，即聚合物表面的微型凹坑阵列可以显著提高具有压敏强度的可逆粘附性。本研究的前提是，通过选择适当的几何和机械性能以及预加载程序，可以为各种应用量身定制凹坑表面。这种裁剪的核心是对粘附和脱粘机制的基本多尺度理解。研究小组计划通过以下三个研究重点，在广泛的尺度上发展对聚合物表面凹坑可逆粘附的基本理解：(i)制造尺寸从厘米到微米不等的表面凹坑。牵引分离关系和拉拔力的测量。建模和模拟。该项目将由一个协同团队进行，他们在微加工、粘附力学、建模和仿真方面具有互补的专业知识。

This award supports fundamental research on the mechanics of cratered surfaces. Reversible adhesives are designed to form temporary bonds, and ideally can be reusable and capable of strong bonding. Such reversible adhesives can find wide applications in vertical mounting and climbing, releasable wafer and chip handling, as well as reusable bio-integrated electronics. It is well known that reversible adhesion can be achieved through surface interactions such as van der Waals (vdW), capillary, and electrostatic forces as well as volume effects such as suction. Adhesion due to surface interactions has been well studied for gecko-inspired microfibrils with different tip shapes including the concave shape. But the contribution from suction has been widely neglected at microscale. However, manufacturing microfibrils with large aspect ratio can be expensive and time-consuming. If an array of meso-scale craters could provide combined high adhesive strength and reversibility, they may become a practical substitute for microfibrils. The results of this research will guide the design and optimization of cratered surfaces and give a definitive answer to the debate of the suction effect across a broad range of scales. It will also create a pathway for developing a new class of superior adhesives for various applications in engineering and medicine. Building upon the strong track record of previous educational and outreach activities, the PIs will continue to provide research opportunities specifically designed for undergraduate and high-school students from minority institutes through NASCENT REU and women in engineering programs (WEP) at UT Austin.The research objective of this research is to test the hypothesis that arrays of miniature craters on polymer surfaces can lead to significantly improved reversible adhesion with pressure-sensitive strengths. The premise of this research is that cratered surfaces can be tailored for various applications, by choosing proper geometric and mechanical properties, as well as the preloading program. Central to this tailoring is a fundamental multi-scale understanding of the adhesion and decohesion mechanisms. The research team plans to develop a fundamental understanding of reversible adhesion of cratered polymeric surfaces in a broad range of scales through the following three research thrusts: (i) Fabrication of surface craters with sizes ranging from centimeters to micrometers. (ii) Measurements of traction-separation relations and pull-off forces. (iii) Modeling and simulation. The project will be carried out by a synergetic team with complementary expertise in microfabrication, adhesion mechanics, modeling, and simulation.