Thermal and directed motion in molecular friction processes investigated by atomic and photonic force microscopy

摩擦是一个复杂的能量耗散过程，在大多数长度尺度、时间尺度和跨学科上都很重要。有几种理论接近摩擦的分子起源，但仍然缺乏全面的理解。通常，摩擦由摩擦系数量化。两个主要路线来确定摩擦系数，无论是从定向运动或从热运动，可以addressed.In这里，我们使用的互补方法原子力显微镜（AFM）和光子力显微镜（PFM）的组合，以获得更好地了解分子摩擦软（生物）接口。为了实现这一目标，我们提出了方向和频率依赖于测量不同的珠表面模型系统，这是装饰与定义明确的结合伙伴。我们特别感兴趣的是，从定向运动和热运动中获得的摩擦系数是如何相关的。在这种情况下，我们将解决的问题，如何单分子摩擦和粘附。最后，我们将研究分子摩擦中的协同性，我们认为这是理解分子摩擦特性如何决定宏观摩擦的关键，我们的综合实验方法将从多个角度对摩擦的分子起源产生前所未有的见解，这将有助于更好地理解功能化界面和水凝胶以及生物运输过程。

Friction is a complex process of energy dissipation, which is important on most length scales, time scales and across disciplines. Several theories approach the molecular origin of friction, but a comprehensive understanding is still missing. Usually, friction is quantified by a friction coefficient. Two main routes to determine the friction coefficient, either from a directed motion or from thermal motion, can be addressed.Here we use a combination of the complementary approaches Atomic Force Microscopy(AFM) and Photonic Force Microscopy (PFM) to obtain a better understanding of molecular friction at soft (bio)interfaces. Towards that aim, we propose direction and frequency dependent measurements on different bead-surface model systems, which are decorated with well-defined binding partners. We are in particular interested, how the friction coefficients obtained from directed and thermal motion are related. In this context, we will address the question on how single molecule friction and adhesion are related. Finally, we will investigate cooperativity in molecular friction, which we believe is key in understanding how molecular friction properties determine macroscopic friction.Altogether our combined experimental approach will yield unprecedented insights into themolecular origins of frictions from various perspectives, which will help to better understand functionalized interfaces and hydrogels as well as biological transport processes.